POISON UNKNOWN

• Chapter I. In the Laboratory
• Chapter II. Unnatural Death?
• Chapter III. McCleod States the Case
• Chapter IV. Some Discoveries
• Chapter V. The Poisoned Dart
• Chapter VI. Unwilling Sleuth
• Chapter VII. Various Evidence
• Chapter VIII. One Alibi
• Chapter IX. The Mysterious Mr. Smith
• Chapter X. A Quarrel and a Chase
• Chapter XI. Second Murder
• Chapter XII. The Green Button
• Chapter XIII. A Night Alarm
• Chapter XIV. Mr. Smith is Caught
• Chapter XV. An Explanation
• Chapter XVI. The Trail in London
• Chapter XVII. The Bloodstain
• Chapter XVIII. Danton Remembers
• Chapter XIX. The Dart Again
• Chapter XX. The Whole Story

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CHAPTER I
In the Laboratory

FROM the rack on the bench before him Paul Danton selected a test tube and held it up to the light. If his theories were justified by experiment, the two or three inches of colourless fluid which it contained would be enough to poison every member of the Juliot Research Institute. As he stood there looking at it the thought came to him, and with it the reflection that it might be worse employed. They would die instantly, painlessly, in a way no man had died before, and no man in the world would recognise such symptoms as appeared except himself. He let his mind play with the idea. Eighteen months of forced association with distasteful colleagues had come near to transforming dislike into hatred; and only a little while ago, while on the threshold of what would probably be the great success of his life, he had realised the probability that another would take the credit for the work he had done.

His firm, almost ascetic face was grim as he changed the tube to his left hand and picked up a short glass rod. He dipped it into the liquid and withdrew it. Upon the tip a single transparent drop gleamed in the sunlight streaming through the windows, to all appearance as harmless as water. But, as a careless movement allowed it to drip on to the hand holding the tube, he moved over to the sink. In spite of a contempt for poisons bred by familiarity, he rinsed his hands once, and a second time, before picking up the tube again.

For a few seconds he eyed it in a kind of fascination. Then, with the rod, he gently scratched the inner surface of the glass below the level of the fluid. Abruptly, as if by miracle, a little blur of crystals materialised. All at once the contents changed to a white, encrusted mass. His expression was unaltered; the uplifted hand did not tremble, but he drew a single deep breath.

Tests had still to be made, but he was already sure. The few grammes of crystal represented an alkaloid which, to human knowledge, had never existed in its pure state, if at all: a new and powerful drug, of immense potentialities and dangers. Experiments had still to be made, chemically and on living animals; but half his work was done. He prodded the stuff once or twice tentatively. Then his face darkened.

"The old swine!" he muttered. "Serve him right if—"

He had spoken the last words audibly. All at once, with a guilty start, he turned his head, with the feeling that someone was watching him. The room was empty. Then, through the open door, he fancied he heard something. It was the sound of a furtive movement on the cement floor outside. He waited, but it was not repeated. For half a minute nothing happened. His momentary tenseness had relaxed when at last he heard the tread of footsteps approaching along the corridor. Something familiar in them made him stiffen again. He looked at the tube, gripping it fiercely. The steps were very near. On a sudden impulse he smashed the tube violently into the waste box at his feet. Appalled by his own action, he stared for a moment at the twinkling points of broken glass before he looked up to meet the eyes of the man in the doorway. It was a complete stranger.

In the first shock of surprise, Danton stood there stupidly. His first coherent thought was that it must be a traveller—a traveller of that cultured, learned type which deals with the more complicated scientific requisites. The next instant, without knowing why, he had changed his mind. The man was neatly, accurately dressed in an unobtrusive suit of dark grey. His rather plump, hairless face expressed nothing but a mild benevolence mingled with apology. There was nothing in the least remarkable about his appearance, except the unusually keen blue eyes which were turned on Danton in a look of inquiry.

"Pardon me," he said. "I was looking for Professor Roseland. Could you direct me?"

There was a distinct pause before Danton answered, and he obviously found difficulty in speaking. With a manifest effort he attempted to assume a more amiable expression than that which must have first greeted the stranger. His eyes dropped for a moment to the waste box, and he swallowed uneasily.

"I don't know," he said at last. "I doubt if you can see him. The Professor— Had you an appointment?"

"In a manner of speaking." A disarming smile came with the words. "He was good enough to suggest that I might drop in—"

"Oh." Still Danton hesitated. "He's been away. Probably he's not back yet—"

"He might have spoken of me? My name is Smith—John Smith?"

He waited, as though expecting some comment or a return introduction, but Danton did not gratify him. He stood eyeing the man with uncompromising coldness; but the stranger smiled again.

"I think I have the pleasure of addressing Mr. Danton?"

Danton frowned. "That's my name. But I'm afraid—"

"I saw it on the door. I am sorry to interrupt you—if you are busy?" He stopped, and there might have been a hidden significance in the words, but Danton said nothing. "I had already tried one room in vain—Mr. Hope's, I think? Er—Professor Roseland?"

"The attendant might know." The young man's manner was brusque to the point of rudeness. "Or ask at the house. He may be away still."

He half turned away, but Smith failed to take the hint. Inclining his head slightly in acknowledgement, he advanced a couple of steps into the room, peering at the bottles and apparatus on the bench.

"Research?" he asked. "Fascinating work, isn't it? But exasperating.... One never knows if months have been wasted—and if one succeeds, someone else may get the glory."

Danton started a little, perhaps in surprise at the echo of his own thoughts of a moment before. He faced the man again, with suspicion in his eyes.

"If you succeed?" he said stiffly. "I don't understand."

"Oh, I mean that, while you are working here, someone in—Germany, say, or America, may anticipate you. After all, there is a good deal of luck in it, isn't there?"

Danton's nod of assent had the bare civility given to a bore whom one is trying to discourage; but Smith seemed to be impervious to discourtesy. He moved a little nearer, reading the names on the bottles standing on the bench. As if accidentally, Danton himself shifted his position so that he came between the stranger and his apparatus.

"Ah, the alkaloids?" It was almost a statement. "Might I ask which group?"

"You're a chemist yourself?"

Surprise forced the question from Danton against his will. Mr. Smith, he thought, must be a chemist, and a chemist of some ability, if, from so cursory an examination of the materials used he could tell the nature of the experiments. Instinctively his outstretched arm covered the open note-book on the bench beside him. Smith noted the action, and smiled deprecatingly.

"You might say that I was a chemist once," he explained. "Before the war... Since—" He shrugged his shoulders, with a suggestion of something foreign in the gesture. "Now, I interest myself only in the work of others."

"I see." Danton's chilling brevity made it sufficiently clear that he had no intention of allowing the stranger to interest himself further in his own experiments. Manifestly he wanted to be rid of him; but Smith would not go. "The Professor probably isn't back," he said after a slight hesitation. "I should call later and ask at the lodge. You might—"

He broke off to look towards the door. Smith turned to follow the direction of his glance. Another young man was on the point of entering. From the overalls which he wore he was evidently a student; but in all other respects he presented a marked contrast to Danton. Well built, and evidently once athletic; but a little tending to fatness; rather excessively hearty in manner; slightly clumsy in movement, and almost too fresh-complexioned, he resembled an amiable, overgrown schoolboy. He did not immediately see Smith standing to one side of the door.

"I say, Danton," he broke out at once, "how about just toddling out for— Oh, sorry! Didn't know you'd anyone here—"

"Not at all." Smith intervened before Danton could speak. "I was only asking Mr. Danton where I could find Professor Roseland. He was kind enough to suggest inquiring at the lodge—"

The slightest possible suggestion of sarcasm in the last sentence nettled Danton.

"I don't expect he's back—" he began. "You see, Hope—"

"Oh, yes, he is!" Hope rejoined cheerfully. "At least, the indicator says 'In'. Have you tried his room?"

"No," Danton snapped. Hope's evident desire to be helpful seemed to accentuate his own discourtesy. "Probably the attendant—"

"Couche isn't at the lodge—I've just come in," Hope interrupted. Danton's manner puzzled him. He turned to the stranger. "I'll take you along there to see, if you like, Mr...?"

"Smith is my name—John Smith. It would be very good of you, Mr. Hope. I believe that I looked into your room a few minutes ago, but you were out...?"

"Oh, I'm not one of the early birds. I just dropped in to see the place hadn't been burnt down, and I'm just popping out again. It's no trouble... See you later, Danton."

Smith had followed his new guide into the corridor before Danton seemed to make up his mind. He crossed the room quickly, and hurried after them.

"I'll just come along, I think," he said. "I'd like a word with Roseland—if he's there."

Smith gave a quick glance at him; then his eyes seemed to stray back to the laboratory. Danton saw the look; his hand went to his pocket. He closed the door.

"I'll just lock up," he said. "That fool Couche might start clearing up."

Hope raised his eyebrows slightly as the key clicked. His own laboratory was always open to anyone who chose to come along, and that Danton should be so careful was outside his experience. He sensed an antagonism between his two companions, and his cheerful nature seemed to be embarrassed by it. They went along the corridor in silence almost until they reached the entrance hall. Smith ventured to break it.

"There are a number of students here?" he asked conversationally. He looked at Danton, evidently expecting the answer from him. "I was not aware—"

"Four."

The monosyllable was discouraging enough; but Hope stepped into the breach.

"Four of us and Seymour," he expanded. "He's the demonstrator—a cut above the likes of us!" He grinned. "Turn left here. That's the lodge—where Couche ought to be but isn't if ever you want him—"

"Couche?"

"The attendant, porter, odd-jobs-man and the rest. He's a regular Pooh-Bah. And it's my belief he has the power of making himself invisible whenever one wants him in any of his capacities.... Hullo! What the devil—?"

This time, at least, the attendant failed to live up to the reputation Hope had given him; for as they turned the corner he was plainly to be seen. It was the unexpectedness of his attitude which had caused Hope's exclamation. He was stooping down beside the door leading to the Professor's laboratory, apparently engaged in trying to peer through the keyhole. A girl was standing beside him, and though he could not remember ever having seen her, there was something which conveyed to Danton an odd suggestion of familiarity. He was racking his memory to place the slight, almost boyish figure and the shock of unruly brown hair when Hope enlightened him.

"Why, that's old Roseland's daughter! What on earth—?"

Before he had finished the question, Danton had hurried forward. The attendant was still intent upon the keyhole when he reached the door.

"What's the matter, Couche?" he demanded. "Anything wrong?"

Couche started. Evidently he had been too much occupied to hear their approach. Red in the face, and more than a little embarrassed, he straightened himself and faced them.

"I don't know, sir," he said hesitantly. "You see, Mr. Danton, sir, the young lady—Miss Roseland—will have it that the Professor has come back and must be here, and if he's here he must be in his room. But the door's locked, and we've knocked and there's no answer. So I looked through the keyhole—"

The girl interrupted him. "You see, Mr.—Mr. Danton, my father was definitely coming back before this morning," she explained, and there was a note of anxiety in her voice. "And we know that, as a matter of fact, he has come back, because the suitcase he took with him for the week-end is in the house. But we can't find him anywhere and no one has seen him. So my uncle, Dr. Boynley, suggested that he might have come back some time very early this morning and have come here—"

She broke off, leaving the sentence unfinished. Danton considered.

"I don't expect there's anything to worry about, Miss Roseland," he said. "If Professor Roseland came back late, he mightn't have wanted to disturb you. And, if he came in here, it's quite possible that he's gone out into the town or somewhere."

"The indicator said 'In'," Smith supplied in a soft, detached voice. "But then, perhaps he wouldn't change it?"

"Then it'd be the first time since I've known him, sir," Couche broke in eagerly. He was obviously torn between the two conflicting views of the situation. "Besides, sir, if he isn't here, his hat is!"

"His hat?"

"On the floor, sir. You can just see it through the keyhole. By the bench there."

He stood aside to make room, and Danton, with obvious reluctance, obediently bent down. Only a small section of the room was visible, and of the Professor himself there was no sign; but undeniably the shapeless piece of felt was the covering which normally adorned the head of Professor Roseland, and if the Professor had another hat, Danton had never seen it. He was frowning a little as he stood up.

"But, even so—" he began.

"Hang it all, Danton, it looks fishy!" Hope intervened. "The old boy—Professor Roseland, I mean—wouldn't buzz off anywhere without his hat, would he?"

Reluctant to be convinced, Danton could find no immediate explanation. He stood staring at the door without answering.

"You see, some of daddy's experiments are dangerous—poison gases and things," Sylvia Roseland broke the silence. "Isn't it possible that he—that something—something went wrong? That he just looked in here to see how some experiment was going, and that—that—?"

"I suppose it's—possible," Danton admitted. "But you must remember he's used to dealing with dangerous substances. Personally, I don't see that there's much to worry about—"

"But—but he might be there! He might be dying—or hurt! Only think, if he were in there, and we were too late—"

"That certainly would be pretty ghastly, Danton," Hope protested. "Isn't there a key or something—just to make sure? After all, if he's not there, there's no harm done."

Danton shrugged his shoulders slightly and looked at Couche.

"Well, sir, there is a key," the attendant said hesitantly. "My pass-key, that is.... But I'd strict orders, sir, never to go in if the door was locked, or unless he gave permission... I don't see that I can risk it, sir."

"But you must!" The girl's agitation seemed to have increased following Danton's grudging admission of the possibility of accident. She looked from one to the other appealingly. "We've got to see! We must hurry! If anything were wrong—"

"Very well. You'd better get it, Couche." Danton gave way apparently in spite of his own disagreement. "You can say Miss Roseland and I insisted."

"But, sir—"

"Get it. Sharp!"

As the attendant started towards the lodge, Danton turned to the girl.

"I think you're fancying things," he said bluntly. "No doubt there's some perfectly simple explanation. And, really, it isn't very often that scientists poison themselves—"

"Perhaps I'm being stupid." Unsuccessfully the girl attempted to smile. "But I couldn't help wondering... You work here, don't you? I've heard Francis mention your name."

"Francis?" Danton asked blankly.

"Francis Seymour—we're engaged, you know. He's a demonstrator or something here, isn't he?"

"Seymour? Yes." Somehow Danton felt at a loss for anything more to say. It had never occurred to him that she might be engaged at all, and that the man should be someone like Seymour, who seemed to have scarcely an ambition or an idea outside his work, rather staggered him. "I didn't know," he said lamely.

"Oh, it's not been announced very long. We were engaged two months ago—privately. I've been working in London—" Abruptly remembering, she broke off and glanced at the door. "Where is Couche?" she demanded impatiently, and then added almost to herself: "But I don't see what could have happened. Only Couche said something about a new poison gas—"

"Poison gas?" Danton's brow wrinkled. "First I'd heard of it... But then, probably I shouldn't. How would Couche get to know?"

"I don't know. He didn't say—Mr. Hope, did he say anything to you?"

"Me? Good Lord, no! I've hardly spoken to him for a week, except when he ticked me off for—"

But with his denial the girl had lost interest in the rest of what he was saying. For the first time she seemed to notice Smith.

"This gentleman—?"

"Oh, this is Mr.—Mr. Smith. He wanted to see the Professor. I understand that he had an appointment—"

"Not an appointment." Smith bowed acknowledgement of the introduction before making the correction. "But the Professor said that he would be pleased to see me if I happened to be in the neighbourhood, and mentioned that he would be returning to-day. He was attending the Pharmacological Conference in London this week-end, I believe?"

"Yes. He went on Friday evening. He was to have been back to-day.... Oh, we must do something. Where is—? Ah!"

Her face lightened as she looked past them up the passage. Danton turned to see Couche coming towards them, jingling a ring of keys, but obviously dubious. But he had not returned alone. Seymour was with him, and the big demonstrator had evidently hurried there immediately upon his arrival. He wore a "Teddy-bear" coat which added bulk even to his large frame, and there was a suit-case in his hand. He was frowning, and his face was pale.

"Francis!" Sylvia Roseland hurried to meet him. "I'm so glad you've come..."

"Sylvia darling! What is it? Couche says—"

He looked from the girl to Danton, who shrugged his shoulders.

"Miss Roseland thinks that the Professor may have had an accident in his laboratory," he explained. "The door's locked."

"An accident? Why should he?" Seymour screwed up his eyes according to his habit when faced with a difficult problem. "But what's this about poison gas? I've heard nothing—"

"Nor have I. Probably imagination."

"It isn't, sir!" Couche broke out indignantly. "I tell you I saw the—"

He stopped abruptly, as though on the verge of a disclosure which, on second thoughts, he decided not to make. Seymour eyed him and frowned.

"Francis, we must see!" the girl urged. "Make him unlock the door!"

"Well." Seymour had the air of having comprehended the situation and made his decision. "Open it, Couche... Here, give me the key."

He took it from the reluctant hand of the attendant, who still muttered something about the Professor's orders, and inserted it into the lock. Then he hesitated. Deliberately he knocked three times on the wood and listened. Sylvia stood beside him breathing quickly, with her hand at her throat. With a click the key turned, and Seymour pushed the door open just far enough to put his head inside. Then the key dropped from his hand, tinkling on to the cement floor. With an exclamation he thrust the door open and dashed into the room.

"Good God! What—?"

The others were at his heels, but in the first moment the big form of the demonstrator prevented their seeing what had made him exclaim. He turned to call over his shoulder.

"Sylvia! Wait— Don't come in!"

In the same instant they saw. The body of Professor Roseland lay on its back in the narrow space between the bench and the wall, sprawling awkwardly with fixed, sightless eyes staring at the ceiling. At the first glance the attitude of the limbs and the ghastly pallor of the face told their own story.

"Daddy! Daddy!"

Disregarding Seymour's warning, Sylvia Roseland pushed past Hope and Danton and threw herself on her knees beside the body; but as she stretched out her arms Seymour gently pushed her back.

"Sylvia! Don't! He may not be—"

For a moment she knelt there, gazing down at the waxen face with horrified eyes. Even to her it must have been obvious that there was no ground for the hope which the demonstrator's words had seemed to suggest. Professor Roseland had evidently been dead for some hours. He was still in his overcoat; the hat which had been visible through the keyhole appeared to have rolled from his head as he fell. Beside his outstretched left hand scattered splinters of broken glass suggested that he had been holding something when he collapsed; the cork of a large flask or bottle was still clutched in the right.

There was a moment's silence in the room. Then the girl seemed to apprehend the truth. With a convulsive sob she rose to her feet, covering her face in her hands. Bending down, Seymour stretched out his hand and felt the thin, wrinkled wrist. He looked at the other three men and nodded.

"Dead," he said unnecessarily in a subdued voice. "Dead some time. I don't know how long—"

"Allow me."

All of them turned at the polite voice. Smith, whose very existence they had forgotten, pushed between Hope and the attendant and came forward. Seymour stared at him as though he saw him for the first time.

"Who—who's this?"

"Mr. John Smith," Danton answered expressionlessly. "He wanted to see the Professor..."

"Perhaps I could help?"

Smith seemed to take permission for granted. He had squeezed himself into the narrow space beside the demonstrator, and was already beginning his examination, with a deftness of touch which suggested the professional before Seymour found anything to say.

"You're a doctor?" he demanded.

"I hold a medical degree," Smith replied without looking up. "Ah!"

His finger shot out abruptly, pointing to the side of the head. In the sparse, iron-grey hair, there was visible the dark stain of congealed blood. Hope gave a startled exclamation as Smith bent forward gently parting the matted locks to look at the wound.

"Lord! Murdered?"

Smith gave no sign of having heard. He finished what he was doing; then stood up, glanced at his wrist watch, and turned to Seymour.

"It is now half-past ten," he said precisely. "Professor Roseland has been dead for at least forty-eight hours—probably more... The cause of death, from a superficial view, would seem to have been heart failure—"

"Heart failure? Oh." There was almost as much disappointment as relief in Hope's voice. Smith looked slowly up at him, and he flushed. "I mean to say—"

"Heart failure," Smith repeated quietly. "But the question remains how it was induced. Many poisons, Mr. Hope, simulate—"

"That's nonsense!" Danton snapped sharply. "The wound—the blood on his head...?"

Smith pointed towards the wall just beside the window. On the rounded end of an iron support which jutted out some eighteen inches into the room, there was a dark smear against the white freshness of the paint. Looking closely, it was possible even to see a grey hair embedded in it.

"Perhaps he struck his head in falling," Smith said. "The head wound is slight—not much more than a scratch. It would not have caused death in a normal man—hardly unconsciousness. It was inflicted about the time of death... I can only repeat that, either Professor Roseland fell and, having a weak heart, died of shock, or—"

"Or?" The girl had been standing in silence, her hands clutched to her breast. "Or what?... You can't mean—"

"Or—the cause of death was something not at once apparent," Smith replied.

"I don't see..." Seymour put his hand to his forehead and paused. "Had he a weak heart? I didn't know... He never said anything—"

"Almost certainly his heart was weak. He probably died almost as he struck the bar. Of course, the blow on the head might have caused the heart failure, except that, bearing the position of the bracket in mind, he could only hit it by lying down. Perhaps he fainted. If not..."

He looked again at the body. His glance seemed to rest for a moment on the smashed fragments of glass beside it; then switched to the rows of bottles on the bench above.

"You think he was poisoned? That's ridiculous!" Danton broke out as he saw the look. "Why—"

Seymour drew a deep breath. "You mean—he might have poisoned himself?" he asked. "Or—or someone else—? Murder!"

Smith smiled slightly. "Or, taking a less sinister view, death might have been due to natural causes not apparent on a casual examination," he pointed out.

"Murder, sir? You said murder?" Couche, who had so far remained hovering in the background, started forward suddenly. "He was hit on the head, sir?"

"Don't!" Sylvia Roseland swayed a little. "It couldn't be—"

Smith shook his head at the attendant. "Or he hit his head," he suggested.

"Then, sir, they got him! He was warned, sir! He'd been threatened—"

"Warned? Who?" Seymour demanded. "What are you talking about?"

Couche looked from the demonstrator to the girl, half opened his mouth to speak, and appeared to think better of it. His face assumed an expression of mulish obstinacy.

"I know what I know, sir," he said. "I'll tell it at the right time—"

Smith raised his eyebrows. His face showed only mild surprise, but he looked at the attendant keenly.

"Murder?" he said, and turned to Seymour. "In any case, you'd better get a doctor—his own for choice. And, if you think—that Mr. Couche's theory has a basis of truth, the police!"

"Police?" Seymour echoed helplessly. "But—"

"The police—at once—if it's murder." Smith looked from one to the other of the horrified faces around him. "It might be a wise precaution to lock the room? And nothing should be touched until they come."

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CHAPTER II
Unnatural Death?

IN the next quarter of an hour, Seymour had given as fine an exhibition of misplaced energy as could well have been wished. He possessed that type of mind which, though careful and logical in the one subject which it comprehends, tends in any crisis of another kind to jump to rash conclusions and take extravagant measures. From the time Smith and Couche had spoken, it never seemed to cross his mind that Roseland's death could be anything but murder. He had rung up the doctor; he had rung up the police. He had anxiously shepherded them all out of the laboratory and assembled them in the library next door but one, and he had not only routed out another student, Wiedermann, from one of the upstairs laboratories, but had telephoned to the rooms of Thursden, the last of the four, to complete his bag. Once Danton had been moved to make a suggestion.

"Wouldn't it be better to wait until the doctor has been?" he asked, not without a trace of contempt. "It's quite possible that, if he's been attending Roseland and this wound is as slight as Mr. Smith says, he'd give a certificate without further trouble... After all, it won't be very enjoyable to the family to have even the suspicion of foul play raised unnecessarily."

"We've got to take precautions," Seymour insisted, with the air of a schoolmaster who resents an impertinence. "Really, Mr. Danton, I am in charge, and must act as I think fit."

Danton said no more. He duly followed the others into the library, and they settled themselves down uncomfortably to wait for the arrival of doctor or police. It was an ordeal to which each member of the party reacted in his or her own way. The demonstrator, with the air of a man who has done everything possible, had seated himself at the head of one of the two long tables, and only an occasional screwing up of the eyes indicated that he was experiencing any emotion other than self-satisfaction. With the girl who sat beside him it was different. White-faced and tense, she leant forward a little in her chair, staring at the opposite wall, with a handkerchief crushed to a tight ball in one hand of which the knuckles showed white. Couche and Smith, at the foot of the table, made an oddly assorted pair. The attendant's lips were moving as though he was rehearsing an imaginary dialogue with the police; Smith was less moved than anyone. His face was absolutely expressionless, and he scarcely altered his position, except once to produce a pocket-book and scribble a few lines in it.

By a common impulse the three students had gathered at the other table, as far away from the demonstrator as possible. Danton sat a little apart, in a mood between gloomy preoccupation with his own thoughts and impatience at what he evidently thought was the demonstrator's officiousness. Hope and the thin, saturnine Wiedermann, were whispering together, and Wiedermann at least seemed to find reason for amusement.

"Old Seymour is enjoying himself!" he sneered. "Quite the little Sherlock, isn't he? Wonder he bothered to send for the police until he'd provided a ready-made solution off his own bat."

"Oh well, I suppose he feels the responsibility," was the more charitable opinion of Hope. "After all, now that old Roseland's popped off he's acting head, I suppose. Don't believe he likes it any more than I would."

"He suffers from the desperate carefulness of inefficiency? Maybe you're right. Funny to think of him in a business like this."

"He's a good chemist—" Hope began defensively, if a little obscurely.

"Oh, he's all right on his subject—or manages to make people think he is. Apart from that he's an ass... I say, the girl's a peach, isn't she? Fancy her falling for Seymour!"

Danton caught the words and looked round distastefully. To Wiedermann, most girls who were passably good-looking were among the more interesting objects in the world. It was one of several reasons why Danton disliked him, and at that time it grated particularly on nerves which were more than a little on edge. Wiedermann saw the look and grinned.

"Well, she looks pretty bad," Hope rejoined. "She doesn't like this if Seymour does.... Looks as though she'd faint at any moment."

Danton glanced across. Hope's diagnosis was undoubtedly justified, and he felt a wave of irritation at the stupidity of the demonstrator in subjecting her to the unnecessary ordeal. Of course, it was Seymour's business, both as her fiancé and as the person temporarily in charge; but then, Seymour had not the type of mind which could appreciate the feelings of a girl waiting like that when her father had just been found dead. She was certainly on the point of collapse. He heard Wiedermann chuckle about something, and guessed that his notice of the girl had been observed; but instead of putting him off it decided him. He rose to his feet and stepped across to Seymour.

"Look here, Mr. Seymour, it may be all right keeping the rest of us hanging about here," he said. "But Miss Roseland has had all she can stand. You'll be having her faint any minute. And anyway, there's no sense in keeping her here. She can't tell the police any more about the finding of the body than we can; and she's been away, so that she probably doesn't know much about his home life. You'd do better to get her uncle—Dr. Boynley—and take her home. The housekeeper could look after her."

Surprise and anger were blended in Seymour's face. He swallowed before he spoke, in what was evidently meant to be a tone of crushing authority.

"Really, Mr. Danton!" he protested. "I can appreciate your chivalrous motives, of course, but I am perfectly capable of looking after Miss Roseland. She is perfectly—perfectly—"

He had glanced towards Sylvia Roseland as he spoke, and for the first time seemed to see her distress. A spasm of something like anguish passed over his face, and his voice as he spoke again was full of anxiety.

"Sylvia!" he cried. "Sylvia! Are you all right?"

The girl did not seem to have heard what they had been saying, but Seymour's words roused her. She made a pathetic attempt at a smile and sat upright.

"I—I'm quite well, Francis," she faltered. "It's nothing... But this waiting—"

"Mr. Danton was suggesting that it would be better if you went back to the house." Seymour gave a quick glance at the student and looked away. "No doubt you are feeling the strain. Mrs. Robertson could take care of you—"

"But—but you'll need me..." In spite of her protestation there was gratitude in her eyes as she glanced from Danton to her fiancé, and Seymour evidently saw it. He bit his lip. "The police will be here—"

"The police won't need you yet. And there isn't much that you can tell them—as Mr. Danton has pointed out." There was an edge on Seymour's voice as he spoke the last words. It seemed as though he was determined to give Danton the credit, much as he hated the intervention of another man. "Your uncle, Dr. Boynley, could no doubt tell them anything which was immediately necessary—"

"I—I don't know." She hesitated, apparently not unaware of the conflicting emotions which animated Seymour. "I—I don't feel—"

Seymour rose to his feet and held out his arm. "I'll... take you home at once," he said firmly. "I should have thought... Couche! Here a minute!"

The attendant started nervously; then rose to his feet and came over to them. Danton was conscious of curious glances from Hope and Wiedermann.

"I'm taking Miss Roseland back to the house," Seymour said in a low voice. "The door of Professor Roseland's laboratory is locked... If the doctor or police should arrive, tell them that I shall be back immediately. You'd better go to the lodge and wait for them."

"Yes, sir. I see, sir."

Ignoring Danton and the others, Seymour guided the girl out of the room. After looking round a little blankly, Couche followed them. The closing of the door was the signal for a relief from the tension which they had all felt.

"Danton, I'm surprised at you!" Wiedermann grinned meaningly. "Cutting Seymour out like that. Thought you didn't go in for—"

Danton's temper, already sorely tried, suddenly broke out. He took a threatening step forward.

"Shut up!" he snapped. "I've had enough of that—"

Hope had risen hurriedly and came between them. But Wiedermann evidently saw the danger signal and did not feel like provoking a conflict. Though there was a sneer in his voice, his next words were apologetic.

"Sorry, old man! Didn't know you were feeling like that."

Danton's anger subsided as suddenly as it had flared out. He felt that he was making a fool of himself and flushed.

"If you must know all about it," he said stiffly, "I simply suggested to Seymour that the girl looked like fainting, and that it would be better if she went home."

"And she took your advice? I noticed that."

Hope, fearful that hostilities were threatening again, stepped in placatingly.

"And the best thing she could do. There was no sense in her staying. A lot of damned nonsense, this idea of Seymour's. If we weren't all students here—"

He broke off as he recalled that there was still a fourth person in the room who had no claim to the title, and as he glanced across at Smith the thought flashed across his mind that the man had an extraordinary capacity for fading out of one's notice. He was sitting as before at the table, and scarcely seemed to have moved; though his eyes were upon them. Hope felt called upon to offer an explanation.

"I'm afraid you must think us a lot of asses," he said frankly. "This affair has set us on edge rather—with the waiting here—"

"If the demonstrator is convinced that a murder has taken place, his precautions are reasonable," Smith rejoined; but from the tone of his voice it was impossible to tell what he thought. "Locking the laboratory door, even at this late hour, might prevent the removal of evidence—or, for that matter, the planting of misleading evidence. And keeping everyone here under his eye until the police arrive might prevent the murderer from making his escape—"

"Good Lord! I never thought of that!" Hope exclaimed blankly. "You mean that he suspects us?"

Smith inclined his head slightly.

"What about him?" Wiedermann asked. "Who's watching him now? I don't see why he isn't in it, too."

"Perhaps the police may share your view," Smith assented courteously; then he smiled. "They may even suspect me!"

Danton looked at him quickly. It had seemed to him that there was a curious intonation in the stranger's voice as he mentioned the last possibility; but his face was blandly unreadable.

"All the same—" Hope began and stopped. The eyes of all four of them were on the door as its opening interrupted the conversation.

The elderly man who entered glanced round the room, and fastened upon Smith as the best source of information.

"What's this about murder?" he demanded. "Mr. Seymour left a message—"

"Mr. Seymour has just gone out, Doctor—?"

"O'Connor. Yes. The attendant told me... Perhaps you can explain?"

"I regret to say that Professor Roseland was found dead in his laboratory a short time ago. There were dubious circumstances about the death, and, in particular, the attendant appeared to be convinced that there was foul play. My own view, which I communicated to Mr. Seymour, was that the Professor had had a heart attack; but Mr. Seymour appears to have adopted the more lurid explanation."

"Heart attack? It's very likely—" The doctor broke off and hesitated. "Of course, I don't know the circumstances," he added in a different tone.

"Professor Roseland suffered from his heart, no doubt?" Smith asked. "You, as his doctor, may be able to give a certificate and set all doubts at rest—"

"Unfortunately, Professor Roseland would never let me examine him." O'Connor frowned. "I knew him as a friend, not as a patient. Though I had warned him—"

"At least you diagnosed a weak heart—" Smith began, but the doctor interrupted him,

"I diagnosed nothing. I merely told him that there were certain indications of it, and advised him to see someone... I don't mind saying that, as it turns out, it's a pity I didn't insist. Matters will have to take their course."

"And consequently, Mr. Seymour's precautions, however excessive—"

"I don't think they're excessive at all," O'Connor snapped. "It's better to be on the safe side than to have everything messed up if anything is wrong."

"But Mr. Seymour—" Danton began, and broke off as the man about whom he was on the point of speaking appeared in the doorway. He hurried forward, followed by a white-haired old man whom three at least of them recognised as Roseland's brother-in-law.

"Glad to see you, doctor," Seymour said nervously. "I hope you can set our minds at rest... This is Dr. Boynley. He tells me—"

"Dr. Boynley and I have already met," O'Connor broke in. "Perhaps he can tell us if the Professor had consulted a physician at all?"

"Not to my knowledge—no, I think not!" Boynley said slowly. "On the other hand, I believe that he was aware that he suffered from heart trouble—"

"Excuse me. You're not a doctor of medicine, I think?"

"Of Letters... Should I say, of Letters only, Doctor?" Boynley gave a wintry smile; and then became grave again. "This has been a great shock, Doctor... If you could reassure us—"

"I hope my examination may do so... The body, I understand, is locked in the Professor's laboratory?"

Seymour felt in his pocket and held out a key. The doctor took it, and turned to leave. As Seymour made as if to accompany him he waved him back.

"If you don't mind," he said, "I'd prefer to be alone... Besides, the police— They're coming now."

If Seymour wished to occupy the centre of the stage, he was fated to be disappointed. Superintendent Carbis had heard of the death of Professor Roseland almost with gratitude; for he had, at the time, been engaged upon a complicated and dubious road case in comparison with which anything would have been a welcome relief. He was not disposed to believe Seymour's excitable message: at the most he expected a sudden death requiring an inquest, or possibly a suicide; but he needed the change. Dr. O'Connor and he had worked amicably together on previous occasions, and it was to the doctor he turned as he entered.

"Morning, Doctor," he greeted him. "You got here before me, I see.... This is a sad affair—all the more to you as a friend of his. Perhaps you could tell me how things stand? I had a message from Mr. Seymour, but—" For the first time he looked at the demonstrator. "Good morning, sir. I'd like to have a word soon with you and the others."

"Good morning, Superintendent," Seymour answered stiffly. "Of course, we are at your service."

The demonstrator was plainly nettled at Carbis's neglect; but the superintendent did not notice it.

"Well, Doctor?"

"I've not made my examination yet," O'Connor said slowly. "But, incidentally, I'd like a word with you in private, Superintendent."

Carbis raised his eyebrows a little in an expression of surprise; then he nodded and looked at Seymour.

"Is there anywhere we could go?" he asked. "If the case is serious, you see, sir, we shall have to take statements."

"There's what the Professor called the office," Seymour suggested. "That is next door to the laboratory—has a door opening from it, in fact. The same key unlocks both doors to the corridor. I have already given it to Dr. O'Connor. The door is the first on the right up the corridor—"

"That will do splendidly... Now, Doctor, I'm at your service."

O'Connor, who had already visited the laboratory on previous occasions, led the way in silence. It was not until he had ushered the superintendent into the little bare room and closed the door behind them that he spoke.

"What do you make of it, Carbis?"

The superintendent hesitated. "That's just what I was asking you," he rejoined. "On the face of it. I'd say it was a case of fools rushing in... From what Seymour said, the murder idea is as flimsy as it could well be. If this man Smith knows anything about medicine, it seems as clear as daylight that Roseland had a heart attack and fell, and I wouldn't give twopence for what the attendant says. So I'm really waiting for you."

The doctor nodded agreement; then he hesitated for a moment.

"Ordinarily, that's just how I should feel myself," he said slowly. "But as it happens... The fact is, this has made me remember a conversation I had with Roseland about nine months ago—when I warned him about his heart, in fact. Perhaps I oughtn't to pay attention to it, because at the time he was quite obviously joking: but it sticks in my mind.... I don't recall the exact words. The substance was that, if ever we found him dead I oughtn't to jump to conclusions about heart failure, as there were plenty of poisons in the laboratory which might give that effect... Of course, it might be coincidence. But, as things are, I'm not sorry that Seymour made such a fuss, even if it's all nonsense."

Carbis pursed his lips as if to whistle. "That's a fact, is it?" he asked. "About the poisons, I mean? You couldn't detect them?"

"I wouldn't say that. You might easily miss them if you had no reason to suspect they were there and didn't do a post-mortem. But, as a matter of fact, practically all poisons leave symptoms that can be found."

"So, if there's a post-mortem, that settles that?"

"Yes. And though this man Couche may be talking nonsense, he gives sufficient reason to have one. I just wanted to give you the tip not to be too sure of 'natural causes'... And now I'll get busy."

He crossed over to the door leading into the laboratory, but it was necessary to use the key again. He looked at Carbis.

"This was locked, too," he said. "That may be important."

Carbis nodded without enthusiasm; for the grounds for suspecting murder seemed to him to be of the flimsiest. He followed the doctor inside. Then a thought struck him.

"Will you have to move the corpse at all?" he asked. "If so, and we're treating this as a possible murder, we ought to photograph it."

"Hardly at all for the present." O'Connor bent down. "He couldn't be lying better if he tried!"

For a minute or two Carbis watched him; then made a rather idle tour of the room. Unfamiliar as he was with the various mysteries of a laboratory, he felt slightly at sea; but so far as he could see at a casual glance, there was nothing very much wrong. If the doctor's verdict favoured murder, he would have to conduct a thorough search; but for the present he was inclined to wait upon events.

"Think I'll just have a word with that attendant, Doctor," he said. "We may as well find out why he's so free with his accusations."

O'Connor only grunted in answer, and Carbis left him to his task. He was on the point of leaving the office by the door through which they had entered when the sight of the telephone made him change his mind. He had left the sergeant at the lodge in the place of Couche, and the private exchange would save time and trouble. Instead of returning to the library, he rang through and gave instructions, and in the interval before Couche arrived made a cursory examination of that room as well. It seemed to be as undisturbed as the laboratory, and he had tired of it even before a knock sounded on the door. He opened it.

"Come in," he invited. "Sit down, will you?"

He indicated one of the three chairs which the room contained, and himself dropped into another. He eyed the attendant closely before he spoke again. The man was obviously nervous, but there was a self-important look about him as well.

"Your name's Couche, isn't it? You're attendant here?"

"Yes, sir."

"Mr. Seymour tells me that on learning of Professor Roseland's death, you expressed the opinion that he had been murdered. Why was that?"

"Well, sir, it's like this." Couche was evidently a little embarrassed. "I clean up the laboratory every day, after the gentlemen have finished, or before they come next morning, sir. And some of them were pretty untidy, always leaving their things about and blaming me if I threw away anything that was wanted. The Professor was as bad as any of them, sir. So I got into the way of always looking at any odd bits of paper that there was any doubt about, sir."

"I see," Carbis assented a little impatiently. He was not greatly interested in Couche's excuses. "Well?"

"Well, sir, I know that Professor Roseland was in danger, sir. It said so on the letter—one I found a bit of, I mean, sir. I can remember the very words. "We have reason to believe that the discovery may be of interest to them, and I wish to warn you to observe all precautions, as they are completely unscrupulous."

He paused, apparently for effect. Carbis frowned.

"Who d'you mean—'we' and 'they'?" he asked. "And what discovery?"

"It was a Government letter, sir; there was a crown on top. Of course, sir, it was the Professor's new gas—"

"What gas?" Carbis demanded, but he sat a little straighter.

"Poison gas, sir. Ten times as deadly—the letter said—as any in use. They'd tested it. He was to go and see them this week-end. He was selling it to them—"

"You didn't keep the letter?"

"No, sir. Of course, I left it with the other papers."

"There was no address at the top?"

"No, sir. It had been torn off... And later on there was a reference to enemy agents, and I knew that meant spies, sir."

Carbis made no comment. He got up, paced the width of the room and back, and stopped again before the attendant.

"Did the letter say anything more?"

"Not that I remember, sir."

Carbis thought. "Right. That's all just now... I'll take a statement later... And, look here, don't go talking all over the shop about this."

"No, sir."

The superintendent was frowning as the door closed. He stood thinking for a moment, made a pace towards the door, and then saw the telephone. He crossed towards it and lifted the receiver.

"That you, Sergeant?" he asked as a voice from the lodge replied. "Get me the Chief Constable—quickly."

---

CHAPTER III
McCleod States the Case

INSPECTOR MCCLEOD paced the wooden platform of the little station with an impatience which he made no effort to hide. On one side, over the roofs of the old town, the golden slopes of the Downs rose in a swelling curve; but if his eyes turned continuously in that direction it was not that he admired the scenery. His thoughts were on the cement monstrosity which constituted a last blot half-way up the hillside, beyond even the red tentacles of the housing estates; and he was wondering just how soon an unpunctual train would allow him to go there.

A signal clattered hopefully and he looked up. The train was just rounding the distant curve, and he moved to a strategic position near the exit. As it steamed into the station, he scanned the windows carefully. A glimpse of a waving arm rewarded him and he hurried forward.

"Got your stuff, Ambrose?" he greeted the large man who was struggling in the carriage doorway with a miscellaneous assortment of baggage. "You have—obviously! We ought to have hired a pantechnicon. Give me that tripod—it's light! Train's late."

"Yes, sir."

"I've been here since noon.... My word, you're loaded to the eyes!"

"Yes, sir." Ambrose somehow deposited himself and baggage on the platform and breathed a sigh of relief. He looked round the station gloomily, noting the absence of porters. "I wasn't sure what we'd need, sir—"

"That's right. Only as we're going to walk—"

"Walk, sir?

There was something like despair in his voice, and McCleod took pity on him.

"Yes. You'd better park most of this stuff somewhere. We're just going up to the Institute now, for a preliminary look round... See that white place up there—looking like a bit of the Wembley exhibition that's lost its way? That's the Institute. That is where we're going to do our stuff—or, as I'm more inclined to think, hunt for mares' nests."

"You don't think there's anything in it, sir? I only saw what was in the papers. They gave heart failure as the cause of death. And it seems probable enough."

"It does. Though there are points... Put that stuff away, and I'll explain as we go. That's why we're walking."

Two minutes later Ambrose returned, having abandoned the heavy baggage and looking accordingly more cheerful. McCleod said nothing until they had passed the barrier and, crossing the main road, had struck a footpath which led through the fields to one side of the town.

"Spotted this way just now," he said. "It's nice and quiet. Now, I'll tell you all about it."

Sergeant Ambrose waited in respectful silence while his superior apparently marshalled his thoughts.

"Professor Charles Roseland," McCleod began after a pause, "is the head—was the head—of the Juliot Research Institute. It's spelt with an 'o', and has no connection with Romeo.... The place was founded under a bequest about ten years ago with the intention of bridging the undoubted gap between the time a brilliant young scientist leaves college, and the time when he can hope to get any kind of university appointment. Unfortunately, it hasn't functioned too well that way, but we'll go into that later. It provides places for a professor, a demonstrator, and four students—"

"I've got their names, sir. Demonstrator, Francis Seymour. Students, Paul Danton, Richard Thursden, Dermot Hope and Gaspar Wiedermann."

"Correct. Well, besides the professorship, the bequest allowed a house for the Professor, attached to the laboratory and with a private door into it, Professor Roseland lived there with his brother-in-law, a retired classical don called Boynley, a housekeeper, Mrs. Robertson, two servants, and the demonstrator, who seems to have been a kind of paying guest. His daughter, Sylvia Roseland, had been studying science in London, and I gather was just on the point of returning to the paternal bosom to help the Professor in his work when he died."

"The wife, sir?"

"Died some years ago. On Friday night, at about seven-thirty, Roseland said good-bye to his brother-in-law and went off to attend some kind of scientific beano in London. His intention was to catch the train to London, stay the week-end there, and come back early on Monday morning. He had a case with him and was wearing his hat and coat. Seymour, the demonstrator, was going to the same show, but he left by the earlier train—"

"Which seems to rule him out, sir?"

"If he went. And there's no reason why he shouldn't have done. We'll check it up... As a matter of actual fact, Seymour seems to have had the least opportunity of anyone. I gather that he'd got a friend with him all the afternoon—an old rowing Blue—and they went off and made whoopee. That wouldn't leave him half an hour all told... Anyway, it seems clear that Roseland never caught that train. He must have gone into the laboratory and died there soon after saying good-bye to Boynley. He was found there on Monday morning."

"And no one had gone into the laboratory all that time, sir?"

"Apparently not. The place more or less closes down at week-ends. The room was locked, and the caretaker had strict instructions not to unlock it without permission. Well, this morning he was overdue, and about ten o'clock Miss Roseland seems to have suggested that he might very well have gone straight to the laboratory on arrival and forgotten all about a detail like breakfast. So she went along to the door leading from the house to the laboratory and nearly fell over his week-end case which was in the passage. Failing to get an answer, she went round to the laboratory, found the attendant, and finally, helped by Seymour and Danton, and accompanied by a man called Smith—who just seems to have blown in for no apparent reason—she got into the room and found her father dead."

"The case, sir? How long had it been there?"

"That's a question. You see, that passage is more or less a dead end, and pretty dark. No one uses it who isn't going to the laboratory, and no one has been found yet who went along it from Friday night until Monday morning. The housekeeper thinks she'd have noticed it, but she's short-sighted, and probably wouldn't. So it might have been put there at any time, or Roseland himself might have left it there."

"But does it matter—"

"We don't know yet. The medical evidence, so far as one can tell before a post-mortem, seems reasonably clear—that Roseland, who had a weak heart, fainted, hit his head, and died a natural death. Then the laboratory attendant steps in. As soon as he knows what's happened, he starts talking about murder and foreign spies and poison gas—a most extraordinary rigmarole which, according to the accounts I've received from the local police, simply makes no sense whatsoever."

"Well, sir, people often do that."

"Yes. But there's a certain amount of plausibility about it in this case. During the war, Roseland was actually engaged on Government work. Quite a lot of those dons were in one way or another. And he seems to have liked to talk about it anyhow. It's quite possible that, on the quiet, he had made some discovery."

"But the spies?"

"Couche's account is circumstantial. Apparently he invariably reads all stray letters that he sees lying about. On two occasions he has seen letters from a Government department referring to the new gas; one warning him to observe secrecy and take precautions against enemy agents; the other fixing an appointment in London for this week-end. Of course, if there's anything in all that, the Pharmacological Conference would come in handy as a blind... I've not seen Couche myself yet—or, for that matter, most of them."

"It should be possible to verify that, sir."

"It should. No doubt it will be, ultimately. Only, if it's anything to do with official secrets, the higher military authorities can be particularly sticky, even with the police, and the Secret Service sometimes likes to be secret about nothing in particular. There may be quite a lot of red tape to unroll.... Anyway, that's the main reason why the local police rather precipitately decided that it was a matter outside their province and called on the C.I.D."

"The main reason? There are others, sir?"

"The other isn't so much a reason as a state of mind. Having once got the murder idea into their heads, or at any rate, having once decided that murder was possible, it seems to have occurred to them that all kinds of people in the immediate neighbourhood had motive, opportunity and means. You see, though they call it pharmacological research, which might mean anything as harmless as a dose of dandelion, as a matter of fact every one in that Institute is working upon some particularly subtle poison. It's no use asking me exactly what, at the moment, because I don't profess to understand the language. I tried to get an idea from Seymour what Professor Roseland's pet subject was, and he murmured something about the 'synthesis of the derivatives of apomorphine', which I've not digested yet. But, roughly speaking, Seymour was dealing with some South American arrow poison—"

"Curare, sir."

"No—less pronounceable. Danton seems to have been trying to make an entirely new alkaloid, improving on Nature. Hope was dealing with aconite, Wiedermann with arsenic, and Thursden with something that sounds like stropanthus—or is it sporanthus? Besides which, they'd all got access to any kind of poison they wanted, and knowledge enough to make it if it wasn't there. Under the circumstances, it looked to the police as though it was simply absurd for a man really to die of a weak heart without any help from someone or other. You can see the attitude. What, they ask, is the use of all these young men who don't like Roseland having all this poison and letting the old boy die naturally? I don't say that it's sound, but there it is."

"Then Professor Roseland wasn't popular?"

"Quite the reverse. If any of them did bump him off, he got what he deserved. From what I hear, he was a scientific thief. He had been quite a good scientist, though he seems to have fallen off. Of recent years, though, he's enhanced his reputation simply by using the brains of the students at the Institute. It's a condition of their studentships that only the Professor can publish results. When he'd finished publishing any work done there, apparently one gathers that Professor Roseland had done everything, but that Mr. So-and-so, whose name is mentioned at the end somewhere, washed out the beakers and handed things to him. It may not be a good motive for murder, but it's the kind of thing which could quite easily get a man's goat."

"No doubt, sir. But it's hardly connected with the spy business, is it?"

"That's one trouble—it isn't. Because it's really not very probable that any of the students were connected with the 'agents of a foreign power' that Couche made so much of. Though it's possible... Well, once having started the ball rolling, murderers grew thicker than blackberries. There was Boynley, who'd had some kind of quarrel with Roseland. Even Couche managed to be a suspect."

"The other man—Smith? The man who was there when they found him?"

"So far as I can see, he doesn't come in at all, except that he was there when they found him. The superintendent says that he produced a letter from Roseland asking him to drop in some time and talk about old times, and that's what he did. But he chose the most inconvenient time possible, just when they found Rosalind dead. Apparently he had rung up on the Friday night, and had been told that Roseland had gone away."

"Then he was here on the Friday?"

"I believe so. But that scarcely makes him guilty of murder... In fact, we've still got to show that there's been a murder, and the odds are against it. Consider the possibilities. First, accidental death of two kinds. It may have been mere heart failure, for Roseland's heart was certainly weak. Or, less probably, it might have been that Roseland made a mistake in some experiment he was making and killed himself. The one thing that lends colour to that is the broken glass at his side. I'm told the bits would make a sort of large jar thing of the kind one might keep a gas in. But I don't believe it myself. The next is suicide. There's no discernible motive, and I imagine one can rule that, out. The third is murder."

"But the fact seems to be, sir, that there's no evidence of murder at all except the talk of this man Couche and the imagination of the local police."

"Helped by the Press. Because though you saw the first account which made it accidental death, I don't mind betting that by now there are papers selling on the London streets hinting at something much more exciting. You see, with so eminent a man as Roseland, the papers are bound to print a fair amount. And with Couche going about hinting at spies and poison gases and so on for the newspaper men to get hold of, and the certainty that he'll say the same stuff at the inquest if he gets a chance, I don't see that the police could very well have avoided making as full an investigation as possible—not unless they wanted to run the risk of getting hauled over the coals pretty thoroughly. No, I don't believe I blame the police. I'd have done the same myself in their place."

"Well, sir, assuming that it was murder, isn't it a question of who had the means and opportunity?"

"If it's a case of a 'subtle Oriental poison'—and they're so rare that I've never met one—all the members of the Institute become suspect automatically, because they represent an accumulation of knowledge about poisons it would be hard to find in a single building anywhere else. And, if it was a poison, it seems pretty clear that it was one of them—unless it was Couche, who might have picked up the knowledge somehow."

"There's the daughter?"

"Admittedly she's a scientist, but she seems to have been fond of her father. Also she wasn't anywhere near the place, if the doctor's estimate is correct. And she hadn't been for weeks. So she hardly matters. I decline to believe that Boynley or the housekeeper or the servants did it in that way... But there's the other possibility. I mean, that he wasn't murdered by poison at all, but that he was simply hit on the head and died of it. It might even be manslaughter—he was pushed over in some sort of quarrel and hit his head. And either of those last two allow anyone to have the means who has the opportunity. All that's necessary is to get into the place."

"There are just the two doors, sir. Were they locked?"

"Actually there are three doors. There's a mysterious sort of basement entrance through the fire-hole; there's the ordinary front door, and the door from the house. All of them would be locked at that time of night, unless the Professor had left the house door open. But all the students and the demonstrator have keys—and, of course, so has Couche. So that's no great help, except so far as it may rule out an outsider."

"On the other hand, sir, if we can't find any trace of poison, it might suggest that it was an outsider. I mean, with such poisons at their disposal, would any of them, planning a deliberate murder, have used such a crude method, or wouldn't poison have been used and an attempt made to make it seem natural death? It seems the obvious thing to do."

"Yes, perhaps. But some people are strangely blind to their opportunities. Still, if we decide that it was murder, we'll have to extract alibis from all of them." He sighed and, as the path turned sharply to the right to join the carriage road to the Institute, pointed to the buildings which were now plainly visible ahead. "Anyhow, there's the place. The lower part to the left is the Professor's house. Ugly, isn't it?"

But Sergeant Ambrose was studying it from a point of view which had nothing to do with the æsthetic. Owing to the slope of the hill, the front walls were considerably higher than those at the back, and such windows as were visible were at a height from the ground which made entry by means of them impossible except with the help of a ladder. A flight of steps led up to the front door, but there was no window within reach.

"If anyone got in, except by the doors, sir," he remarked, "it must have been at the back."

"True. Only, as a matter of fact, the Professor's laboratory is at the back, and the windows there are quite near the ground, I believe. The superintendent said he was having those examined. As I say, we're hunting for mares' nests very hard in this case. So we might find anything. One can never tell what— Hullo!"

The cause of his exclamation was apparently the harmless-looking man who was coming down the carriage-way towards them. The inspector was staring at him as though he could not believe his eyes; but the sergeant could see nothing about the newcomer which seemed to warrant any such attention. He might have been anything; perhaps he was most like some kind of professional man. McCleod seemed to make up his mind and advanced into the road to intercept the stranger.

"Good afternoon," he said. "Mr. Robinson, isn't it?"

The man to whom he spoke stopped, raised his eyebrows slightly, and looked from McCleod to Ambrose. Then he smiled forgivingly.

"Pardon me," he said. "Smith is my name—John Smith."

"It wasn't in 1917," McCleod said bluntly. "I don't expect you remember me—"

"Why, if it isn't Sergeant McCleod—I beg your pardon, I read somewhere that you had been promoted, Inspector." He smiled again. "This is a pleasant meeting—though I suppose we must both regret the event which caused it. No doubt I am right in thinking that it is Professor Roseland's death which brings you?"

McCleod said nothing. He was, as a matter of fact, already regretting that he had said so much. It would certainly have been better to allow Smith to think that he had not been recognised.

"An old acquaintance of mine, Inspector. Our friendship, if I may call it so, dates from the time when we first met and you were a sergeant... And I, of course, was Robinson then. Yes, it was Robinson. That was a pseudonym. I really am Smith. You can look me up!"

"But you really were Robinson!" McCleod rejoined, and stopped himself. "I suppose you'll be staying here for a few days?" he asked casually.

"At the Crown Hotel... I had already informed the superintendent of my intention, Inspector. But I should be delighted if you would look me up. No doubt, in any case, you would like to see me officially. But not now, I imagine?"

"No," McCleod said tonelessly. "Not now."

"In that case, you will excuse me? No doubt you yourself are busy at the moment... Good afternoon."

McCleod did not reply to the salutation. He stood staring after the other's receding back, and Ambrose could make nothing of the expression on his face. At last, without a word, he turned and began to climb the hill. They had gone several yards before he spoke at all. Then it was brief and pointed.

"Blast!" he said fervently.

"You knew him, sir?"

"Oh, no! We were perfect strangers! You must have seen that!"

Ambrose relapsed into an abashed silence. They were nearing the Institute gates before McCleod spoke again.

"There may be something in Couche's tale," he said, half to himself. "It's queer. Here's Mr. Smith-Robinson... And Roseland did Government work in the war—"

"But how did you meet Robinson, sir?" Ambrose ventured rashly.

McCleod smiled mirthlessly. "I tried to get him shot," he said. "And, damn it! I failed!"

---

CHAPTER IV
Some Discoveries

NEVER very cheerful at the best of times, the face of Superintendent Carbis seemed gloomier than ever when he met them at the door of the Institute. He acknowledged McCleod's introduction to Ambrose almost absently, and there was plainly a good deal on his mind.

"What's wrong, Superintendent?" McCleod asked. "You're not looking very happy. Found anything?"

"Wrong?" Carbis eyed him sadly. "Well, I don't know. Yes, we've found several things—too many if anything!"

"That's surely a fault on the right side?" McCleod smiled. "Just what?"

"You'd better see for yourself. I'll take you along to Roseland's room in a minute. Maybe you'd better get a general idea of the place first?"

He led them to a point in the entrance hall from which they could look along both the downstairs corridors, near a flight of steps which evidently led to the first floor.

"You see," he said, "the laboratories themselves are grouped in the shape of a capital 'L' with the house sticking on to the shorter side. Both upstairs and down there's one long corridor and one shorter one. In fact, barring outbuildings, it's just like an 'L'."

"I see," McCleod said patiently. "Like an 'L'."

"That's what I said... Downstairs along the shorter corridor there's the library, a place called the office, and Roseland's laboratory, with the door leading to the house. Above these are Seymour's room and a lab, used by no one in particular. On the longer corridor there are Hope's and Danton's rooms, with a storeroom and a cloakroom, and above Thursden's and Wiedermann's with another storeroom and a cupboard."

"Seems to be plenty of storage room," McCleod murmured. "A handy little place."

The superintendent ignored his levity.

"The door to the right of the entrance leads to the lodge. The telephone exchange is there, and Couche ought to sit there when he's nothing else to do—which, according to him, is never. He seems to be more overworked than a policeman. The basement rooms run right under the building, but half of them aren't used for anything. Couche has a workshop in one, and another is for coals and heating apparatus. That's the general lay-out."

McCleod nodded. "How about locking up?" he asked. "Is the entrance door locked by day?"

"No. With luck or a little assurance, anyone could come in. One would just look at the indicator, see who was out, and, if anyone inquired at all, say you were looking for him. That would be easy."

"I suppose the students lock their rooms?"

"Sometimes, sometimes not. It's all very haphazard, in view of the fact that there's enough stuff to poison a town here. Some of that's supposed to be locked up, but generally isn't."

"But I gather Roseland's door is generally locked?"

"No. It's locked sometimes, and, when it's locked, Couche has been warned to keep out. But you may take it from me that there's no real locking up here in the daytime."

McCleod frowned. "Then anyone could get in while it was open, hide in one of those store-cupboards, say, and be there at night?"

"Exactly. That's one of the depressing things I've found out. Though, actually, it's not so important as it seems.... The place is only locked up at half-past six, and even so all the students and staff have keys."

"So, what at first looked like a closed shop is actually as open as the day?"

"In the day—yes." Carbis sighed, and his gloom increased. "Thanks to the infernally casual way they have of doing things. But one thing we've found in the laboratory has some bearing on this question. You'd better come along and see."

He was leading the way along the passage when the sound of voices from the lodge made him turn to look. The policeman on duty there was arguing with a supercilious-looking young man who had just entered, and who seemed to be trying to push his way past with scant ceremony. Carbis and McCleod barred his way as he succeeded.

"Just a minute, sir!" McCleod requested politely, and no one could have sworn to the faintest possible emphasis on the "sir" which made the young man scowl. "Might I ask what—?"

"What's this? First that fool on the door, and now— If you must know, I was sent for. I had a message from Mr. Seymour—"

"You'll be Mr. Thursden?" Carbis asked. He did not add that the description which had aided his identification had been "a swelled-headed young swine". "Mr. Seymour said he'd sent you word."

"Of course." Thursden looked from one to the other insolently. "I suppose you're policemen? But what's all this about? My landlady says Professor Roseland was murdered. That's absurd!"

"I see, sir," McCleod assented. "But Professor Roseland died suddenly. That's got to be investigated... You were rather late in hearing, sir."

"I've been away," Thursden vouchsafed. "I have just got back."

"To London, sir?"

Thursden stared. "Yes—if you're interested," he said.

McCleod's air was wonderfully humble. "I was wondering if you had perhaps attended the Pharmacological Conference? I believe that Professor Roseland and Mr. Seymour were going there?"

"Conference? Good Lord, no!" Thursden grinned, then again became dignified. "I know nothing about it—or them. I have nothing to say at the moment."

The inspector's eyebrows twitched, but he maintained his attitude of meekness. "Not at the moment? I see," he agreed sweetly. "But I'd be glad if you'd stay available for a little while.... There may be questions we want to ask."

"I was going to stay here until tea-time. That should be sufficient for you."

A slow smile spread over McCleod's face as Thursden turned away without another word and strode towards the stairs. He looked round to meet the furious gaze of the superintendent.

"The young pup!" Carbis exploded. "Just for that, I hope you rub it into him good and hard—even if you can't hang him."

"The Lord has certainly given him a good conceit of himself!" McCleod smiled. "Carbis, I'm surprised at you! You wouldn't have me be rough with him—if he can spare me a moment later?"

Carbis grunted. "That's one alibi, apparently," he said. "And it's one I'll test to the last minute!"

"Yes. And alibis for the staff and students may be important; for it looks as if—assuming there's been a murder—either the students or a friend of Roseland's was involved. If he didn't always lock the door of his laboratory, he certainly did on that particular day. Probably he let the murderer in himself."

"Don't know... That's one of the things we've found. You'd better come along and see."

Following the superintendent up the passage, McCleod noted that the windows on the inner side of the "L" to which Carbis had likened the building could be ruled out as a means of entrance. They were of the type which do not open, except for a six-inch ventilator at the top, and if any unauthorised person had got in otherwise than through the doors, it must be by way of the windows in the laboratories themselves. Carbis stopped before the last door in the corridor and opened it.

"Here," he said.

From a high stool where he had been unsuccessfully trying to make himself comfortable a plain-clothes detective slid to the ground as they entered. He was not the only occupant of the room. Rather to McCleod's surprise, Seymour was standing by the window, looking acutely uncomfortable, and obviously trying not to look at the body which still lay sprawling beside the bench. His face must have betrayed his thoughts, for Carbis hastened to explain.

"Thought that we'd better have someone on hand who knew about all this stuff," he said, waving a hand towards the rows of bottles and apparatus. "You see, it's not impossible that they might have had something to do with it, especially if Couche is speaking the truth. Mr. Seymour was good enough to come and help us. And he's in charge here, anyway."

"Yes, of course." McCleod's assent lacked enthusiasm. "Nothing has been touched here, I suppose?"

"The doctor may have had to shift the body a bit in making his examination, but I don't think so. What d'you think, Mr. Seymour?"

"Pardon?" Seymour turned hastily from looking out of the window. "What do I think?"

"Would you say that the body was lying as it was when you first saw it?"

Seymour looked obediently and quickly averted his eyes.

"Yes," he said nervously. "Oh, yes. I should say that it was."

It might have been pity for the demonstrator or another motive which made McCleod turn to the superintendent.

"I think it would be best if we asked Mr. Seymour any questions which occur to us immediately and get it over," he suggested. "We won't detain him any longer than we have to. No doubt this business has meant a lot of trouble for him and he has plenty to do."

Seymour nodded unhappily. Moving towards the bench, McCleod studied it for a moment, looking from the apparatus upon it to the dead body on the floor and back again.

"I suppose that we must assume something like this," he suggested. "Professor Roseland was going to this conference affair in London. Before he set off to catch the train, he may have thought of something he had to do in here—either he wanted to look at an experiment which was proceeding, or he came to get something. We can't tell whether he did what he intended or not, but for some reason he was standing in front of this bench when he died. The point is this, Mr. Seymour. Can you tell us, from the bottles and apparatus on the bench, what the Professor might have been doing?"

The demonstrator moved forward, screwing up his eyes in the way which seemed habitual to him when in any mental stress. He read the labels on the lines of bottles and scrutinised the flasks and tubing. Then he shook his head.

"There's no apparatus here actually in working order, Inspector," he announced. "It looks as though he'd been going to do something with apparatus and hadn't finished assembling his apparatus yet... I mean to say that, if he was actually using this apparatus, he had been, or was going to, do something about collecting a gas. He might have finished, and have taken part of the apparatus to pieces. As things stand, one cannot possibly say what he was doing. The bottles are just ordinary stuff—solvents and so on."

"A gas, you say?" The question sounded perfectly casual, and McCleod refused to meet the eye of Carbis, who had looked at him significantly. "What sort of gas?"

"There's no means of telling. As I say, the apparatus as it stands couldn't be used at all."

"I see." McCleod pointed towards the fume-cupboard, where the tiny flame of a bunsen still burnt beneath a flask which steamed and bubbled as though the ordinary routine of the laboratory were proceeding. "Who lit that?"

"Why—I suppose Roseland?"

"Two days ago? Nearly three? Wouldn't it boil dry or go out?"

"There's a thermostatic arrangement to regulate the gas," Seymour explained, "and it wouldn't boil dry until those bottles of distilled water were empty... You see, Inspector, in organic experiments particularly it is often necessary to boil things or keep them at a constant temperature for long periods—"

"Yes, I see," McCleod said untruthfully. He eyed the flask dubiously and seemed on the point of asking something else about it, but did not. "I don't know that there's much else occurs to me at the moment—about the laboratory, I mean."

He looked at the superintendent and Ambrose. The sergeant shook his head decidedly, but the superintendent was more courageous.

"Nothing, say in connection with this apparatus, could have caused the Professor's death, Mr. Seymour?" he asked. "Since his heart was so bad, even a bad shock—if something blew up, for example—"

"But there's been no explosion," Seymour objected. "No, I can't imagine anything, unless—"

He glanced towards the scattered fragments of glass on the floor beside the body. McCleod nodded.

"Unless there was something in that bottle? Exactly. I imagine that that's a matter for analysis by experts. There would be some traces?"

"Not necessarily. If the substance was volatile, it might evaporate and leave the glass quite clean. There has been plenty of time for the gas to dissipate."

"Plenty," McCleod agreed, and his tone was significant. "Now, Mr. Seymour, we won't keep you much longer. Just a question or two about yourself. When did you last see the Professor?"

Seymour frowned in an effort to concentrate. "At about six o'clock on Friday evening," he said at last. "In the house. He said that he was following me by the later train—"

"Did he give any reason?"

"None... But I know he wasn't keen on hearing that evening's paper. He'd never agreed with the speaker's views."

"Would you be staying at the same hotel in town?"

"Oh, no." The demonstrator hesitated. "My income is a good deal more moderate than that of Professor Roseland," he said. "He had private means."

"So you wouldn't have seen him that night?"

"No. Nor even next morning, necessarily. You see, the conference split up into different group meetings, and Roseland and I would naturally have been interested in different groups. I never thought of looking out for him until Saturday evening, and then the hall was so crowded that I thought I'd missed him."

"So, for all you know, he might have attended some part of the conference?"

"Well," Seymour answered dubiously, "I should have expected to see him some time. But I needn't have done."

"You yourself caught the earlier train and went straight to the conference?"

"Well, I was early. I walked from the station and stopped on the way for something to eat. I didn't go to the hotel till afterwards."

"You travelled down alone?"

"Why, yes." The general bearing of the questions seemed to dawn upon the demonstrator. He flushed a little. "I don't see, Inspector—"

"Well, it's desirable in these cases to know where everyone was," McCleod soothed him. "You see, if we can rule anyone out altogether—"

"Of course. In other words, you'd like an account of my movements. I don't know where I ought to start. I had a friend who came down in the afternoon in his car. A man called Whitley—a student at the Royal College of Science. We had tea and then he went back. I came back to the house to collect my case—and then, you know the rest."

"None of the students went to the conference?"

"Oh, no. I don't think any were interested."

McCleod considered. "I don't think we need keep you, Mr. Seymour," he said. "No doubt you're needed elsewhere... I'm afraid Miss Roseland must feel this deeply."

"Naturally. Though, I think, at present she's too stunned to realise—"

"It's a good thing she's got you... You've been engaged some time?"

"Privately about two months." Seymour screwed up his eyes. "Professor Roseland consented a few days ago."

"You'd say the Professor had been normal? He didn't mention having made a discovery?"

"No. But if he had made one, he might not have said anything until he published the results. About his work he was very secretive. Almost distrustful."

"Thank you, Mr. Seymour." It was plain that McCleod intended to dismiss the demonstrator. "I don't think we need keep you longer."

Seymour glanced at the superintendent, who in turn shook his head.

"Nothing at the moment. If there should be anything else, we'll ask you later, Mr. Seymour."

The demonstrator inclined his head and moved to the door which McCleod had opened. On the threshold he hesitated for a moment as if about to say something more. Then he went out. McCleod shut the door and frowned a little.

One always feels in these cases that what people don't say would be so much more enlightening than what they do!" he complained. "Now, I wonder what he thought of saying and didn't—or if he couldn't think of anything and wanted to?"

"Wanted to?"

"Well, if he were the murderer, he'd probably feel uncomfortable in the presence of the body—which he obviously did. But he'd hate the idea of letting the police out of his sight as long as he could keep an eye on them and see how they got on."

"Good Lord, you don't think that he—?"

"That's why I turned him out. Does he know, by the way, what discoveries you've made here?"

"Why, no. As it happens, he'd only just come. But, look here, he's done everything possible to see that we'd the opportunity to investigate properly. But for him perhaps no one would have thought that there was a murder at all!"

"Makes no difference. I'm pretty sure that this must be an inside job, so he's got to be classed with the rest."

"I'm not sure that it is. One thing that I've got to show you suggests—" Carbis broke off as another thought struck him. "Besides, he's got an alibi. Roseland was certainly alive after he left to go to London."

"Only we haven't checked the alibi yet... Oh, I'm not suggesting him as Suspect No. 1. Merely taking a few precautions."

Carbis seemed a little nettled. "I just thought that all this scientific stuff might be important," he defended himself. "And he seemed to be the obvious person to explain."

"I shouldn't be surprised if it was. That flask, for example. Wouldn't it be possible for it to have contained something which would give off a gas? Or this broken bottle? If Roseland was poisoned in that way, either of them might have been the means. We'll have to get an expert down, though. Because if Seymour had done it, of course he wouldn't tell us how."

"And we don't know that there's been a murder yet... Though what I've just found strengthens the possibility. Would you like me to show you what we've unearthed up to date, or will you look round yourself?"

"Better show me." McCleod grinned. "Then, if I should have missed them you wouldn't know—and I shan't go thinking I've made a great find, only to learn you beat me to it."

"Well, first there's this." Carbis stepped across to the window at the far end of the room and pointed to the frame near the catch. "See that?"

In common with the rest of the room, the window had evidently been painted comparatively recently; but on the woodwork three or four scratches were faintly visible. McCleod examined them carefully, and finally drew a magnifying-glass from his pocket and looked again.

"What do you make of them?" Carbis asked as he pocketed the glass.

"Just what you do yourself. They're quite fresh. Someone forced that window, and not long ago... Have you tried for prints at all?"

"Not yet. But there's something else here."

Producing an envelope, he shook on to a clean sheet of paper a few woollen fibres of a brownish colour.

"These came from the cement just outside the window. As you'll see, it's pretty rough. I thought I'd better take them off in case they blew away. They can't have been there very long."

McCleod again called the magnifying-glass into operation.

"I should say it was a brown tweed with a check pattern of darker brown," he said after an interval. "Though that's guesswork... Any of the students wear one?"

"Not that I've seen. But they might have changed their clothes."

"Or, for that matter, as you said, this might suggest it wasn't a student at all. It just knocks a bigger hole in the 'sealed room' idea. Any stray thug might have forced this window and got in. Then, if the Professor wasn't poisoned, he might have hit him... What we need on this job is a full medical report."

"That may be some time."

"Yes. All the more since they'll have to look for very subtle and difficult poisons. We can't wait for that. Though we need it badly... Anything else?"

"Yes. Make anything of this? We found it on the bench."

He held out a strip of paper, apparently torn from a larger piece. McCleod took it gingerly by the edges and read it out:

"'Itastuas tariterque. Tariter tariterqui—'" He raised his eyebrows. "What the devil's this?"

"I don't know. It's not Roseland's handwriting. I don't even know what language it is. Latin?"

"Not so far as my memory goes—and yet it's got a vague look of it. Might be cipher? We'll look into it, anyway. And, I suppose, that means getting specimens of handwriting, too. Besides prints... There's really some scope for prints here. The surfaces are beautiful. Between all this glass, and the glossy paint there should be plenty. The trouble will be to decide what prints ought not to be here. The Professor's will be, and Couche's. Then, did any of the students help him in his experiments? Or when were they here? We'll have to test all that. Though, probably, the murderer was the one person who didn't leave any traces."

"There were no visible tracks on the floor which meant anything. Besides, there'd been too many people in here before we started. But we found this."

He laid a leather-covered button, of the kind used for sports coats, on the bench beside the cloth fibres. McCleod eyed it dubiously.

"Why green?" he asked. "I don't believe one would have green buttons with a brown coat like that... Though there's no saying what young men will do these days. Why, even Seymour has that horrible overcoat. He deserves hanging for that!"

"Of course, that might have been dropped any time," Carbis commented. "By the way, we photographed the body. So, if you'd just look at that we could get it moved—"

McCleod inclined his head in assent and crossed the room to where the dead man lay. Standing in a position opposite the apparatus on the bench and near the feet of the corpse, he roughly estimated the distance to the wall-bracket; then, frowning a little, drew a tape measure from his pocket, and proceeded to measure it accurately, noting the result in his pocket-book. After viewing the body from as many angles as the bench and wall allowed, he knelt down and examined the wound on the head, and then produced his magnifying-glass to look again at the bracket.

"There seems to be no doubt that he hit it," he commented, speaking almost to himself. "The traces of blood are plain, and there are one or two hairs. There doesn't seem anything wrong—"

"Why, did you think he hadn't hit it?" Carbis asked. "I thought that that was pretty obvious."

"Perhaps. Only I didn't quite like the way he was lying. If he was standing where he seems to have been, would his head reach the bracket when he fell? Apparently he must have managed it somehow, so he must have wriggled away a little after he was hit... That's why I wondered if the wound on the head had really been caused by the bracket, or if perhaps someone had just smeared the bracket with blood to make it look that way."

"You've got some theory about what happened?" Carbis asked dubiously. "That's why you thought of that?"

McCleod shook his head in denial. It was, in fact, one of his rules not to theorise too soon.

"Only that I don't quite like the way he seems to have fallen. By the way, what's this bracket for?"

Carbis indicated a pulley in the roof. "I asked that. Apparently they use a sort of drum covered with soot for measuring frogs' heart-beats and so on. That takes the spindle containing the drum, and the pulley can make it revolve if they want it."

The inspector nodded absently. He had risen to his feet, but suddenly he knelt down again beside the bracket.

"Superintendent!" he said sharply. "Look here!"

Carbis bent down obediently. McCleod was pointing to the under side of the bracket, but for a moment the superintendent looked without comprehension.

"Well?"

"Don't you see? There's blood—and hairs—on the under side! And it's not dripped down—Roseland's head hit it from underneath!"

"But how could it?"

McCleod rose abruptly, but he did not speak at once. He eyed the body and the bracket for nearly a minute before he answered.

"It couldn't," he said finally. "If Roseland merely fell... I think this clinches it, Carbis. It was murder—staged to look like accident."

---

CHAPTER V
The Poisoned Dart

THERE was a moment's silence. Then, still without saying a word, Superintendent Carbis stepped across to McCleod's side and knelt down to scrutinise the bracket, glancing from it to the corpse and back. He rose to his feet, nodding his head slowly, like a man convinced against his will.

"You're right," he admitted. "But, even so, why underneath?"

McCleod shrugged his shoulders. "I don't know. I'm only sure that, if he fell in any ordinary way, he couldn't have hit it so as to leave that mark."

"Suppose for some reason he'd been lying on the floor and got up suddenly—"

"Could he have hit his head as hard as that?"

"He might." Carbis was dubious. "But if someone had poisoned him, and wanted to make it look either as though he'd died from a knock on the head or from heart failure— Well, one would naturally lift the corpse up and bang it down. Surely?"

McCleod had no answer to make; but Sergeant Ambrose cleared his throat diffidently.

"Well, sir," he said, "I don't say that that wouldn't be the ordinary way of doing it. All the same, if the murderer was a big man and pretty strong, he might have just picked the body up by the collar and the seat of the trousers and swung it against the iron there... It's possible, sir. I could do it all right."

"If it were someone big—" McCleod echoed and stopped, but everyone in the room was thinking of the tall, heavily built figure of the demonstrator who had just left. He went over to the body again and examined the clothing. "Yes, it might have been done that way. I'm not sure that the clothes don't look as if he'd been lifted. When you come to think of it, with a limp thing like a fresh corpse, it might be an easier way of taking aim. The wound is on the side of the head and a little towards the back—as one might expect."

"But why was it done?" Carbis suggested. "Judging by what the doctor says, if poison was used, it was a poison which would pass muster pretty well as heart failure. Why go to all that trouble to create a murder, when the verdict would have been 'Death from natural causes'?"

"Presumably the murderer didn't know the heart was weak. And if Roseland's heart had been normal, a sudden heart attack might have been suspicious." McCleod sighed. "But there's too much supposition about it. We want those medical reports. All we can say at the moment is that it might have happened that way—and it's the only way we can think of up to date... I'd like that body moved, if you've no objection."

"None. Give a hand, Percher."

Between them, Ambrose and the local detective had no difficulty in lifting the body. The Professor had been the type of man who grows thinner with advancing age and, slightly built as he had been, at the time of his death he could not have weighed more than nine stone. McCleod nodded his head dubiously as he noted the ease with which the removal was accomplished, and then stooped to examine the place where the body had lain.

"It's the one spot where no one can have walked since the murder," he said in explanation. "There's the bare possibility that there might be some kind of prints here—"

Carbis stood watching him as he went over every separate square of the parquet flooring with minute care. Suddenly he bent down, stretching out his hand.

"What's that?"

McCleod looked, and in a flash had gripped the superintendent's wrist, just as he was on the point of grasping the object which had attracted his attention.

"Careful!"

"Why? What—"

Very gingerly McCleod picked up the little splinter of wood which had attracted Carbis's attention. It was dark in colour, evidently from some kind of foreign tree, and as he held it up a gummy juice could be seen glistening at the sharp end. McCleod wiped his forehead with his free hand.

"You don't go to museums much, Superintendent?" he asked. "No? Well, unless I'm very much mistaken, if you'd happened to prick yourself on the point of that splinter, you'd have been dead in about five minutes... It's a poison dart."

"Poisoned!" Carbis recoiled a little; then he looked at McCleod significantly. "I think that Mr. Seymour—"

"Is investigating a South American arrow poison? Yes. And he's the right build to have swung the body. And we don't know yet what motive he might have had—perhaps Roseland wasn't so keen on that engagement? And we haven't checked his alibi—"

"If the medical report—"

McCleod drew a sheet of paper towards him from a pile on the bench and laid the dart carefully upon it. Producing his magnifying-glass again, he looked through it for about a minute, concentrating his attention on the point of the splinter.

"I doubt if this has been used," he said at last. "But then, it mightn't have been the only one. There may be another in the clothing—"

"Good God!" Ambrose exclaimed in spite of himself. "If we'd touched it—"

McCleod paid no attention. It had never been his habit to worry about things which had failed to happen.

"The trouble in this case is," he said, "that when we get the medical reports it may not prove anything. This is a research laboratory, and it's possible that any one of the students may know more about his own particular poison than anyone else in the world! The doctors might not be able to spot that a poison had been used. After all, it'll be three days before they really start to analyse for the stuff. And I seem to remember that some vegetable poisons disappear pretty quickly... You might look for another dart, Ambrose. Carefully."

The injunction was scarcely necessary; for Ambrose touched the clothing as though it was red-hot, examining every inch before he laid a finger upon it. In the meantime, McCleod had resumed his examination of the floor. He rose to his feet at last.

"Nothing there," he said. "At least, nothing that could possibly be identified. If only all criminals would wear boot protectors or rubber heels—"

A knock at the door interrupted him. The next moment Seymour entered, in obvious consternation, with Sylvia Roseland just behind him. He advanced straight towards the inspector, and when he spoke the words came in a rush.

"I've just made a discovery, Inspector—a serious discovery which may be important. I don't know what it means, but all things considered I thought that I had better report it to you at once. I can't imagine how it happened—"

"Just a minute, Mr. Seymour," McCleod begged. "Perhaps it would be as well first of all if you told us what had happened."

Seymour drew a deep breath.

"Two of my poisoned darts are gone!" he said. "They've been stolen."

"Two?" McCleod said involuntarily, and then recovered himself. "Your poisoned darts? Oh, yes. Of course, Mr. Seymour, you're researching into some arrow poison, aren't you? You actually use the arrows?"

"There's no other source of supply. You see, I'm investigating the poison—trying to find out what it is. A friend sent them to me from the Upper Amazon country, and I thought— Well, it's rather complicated to explain—"

"But I should like to hear about it," McCleod said softly, and something in his voice made Sylvia Roseland look at him with eyes in which there was a trace of fear. "I'd like to hear right from the beginning."

"Well, my friend told me about this stuff, and from what he said, it seemed to me as though it might be put to some medical use. I suppose you know that experiments have been made in the use of curare as a cure for tetanus?"

McCleod only shook his head.

"The point is that in cases of tetanus people are generally killed by the convulsions which it sets up. The idea of the curare treatment is to paralyse the body, so that there can't be any convulsions. Only curarine paralyses the respiratory muscles as well, so that it's necessary to make the patient breathe by artificial means... You follow me?"

"More or less."

"The curarine treatment hasn't been too successful. It seemed to me, from the symptoms my friend described, that this stuff might be better. But the secret of its preparation is closely guarded by the tribe which uses it, so the only way to get samples was to have the arrows. My friend sent me some."

"Was it more successful than curare?"

"It's hard to say yet. My experiments are still in progress. But I'm inclined to doubt if it will be. Because it appears to produce a curious reaction on the heart, which is generally fatal."

"On the heart?" McCleod echoed. "Yes."

"Naturally with stuff of that sort—the least prick is enough to cause death—I was careful not to leave it lying about. I knew exactly how many darts there were. In fact, I counted them last Wednesday. Danton was there—he's one of the students here. But of course, you know that. He can corroborate the number."

"Danton? I see."

"Well, after leaving you to-day, I counted them again. Miss Roseland was with me at the time. Two of them have gone. The drawer in which they were kept was locked, of course, but it is of a very simple type. It might have been forced."

"Were there any signs of it?"

"No."

McCleod nodded. "So I suppose you thought that you had better come to us so that a warning may be issued regarding the danger attendant upon any careless handling of them?" he asked innocently.

"I thought—I thought—" Seymour began and hesitated. "I thought they might have caused Professor Roseland's death!" he blurted out finally.

"You think Professor Roseland took them?"

"Of course not!" Seymour plainly regarded the Inspector's stupidity as beyond belief. "But if he was killed—"

"Ah." McCleod moved slightly. "You're suggesting murder? But we've no grounds for supposing anything of the sort up to date."

"It mightn't have been murder!" Seymour said desperately.

"If they'd been left lying about—"

"In the Professor's laboratory? Let's understand this, Mr. Seymour. Your view is that, for some unknown reason, someone deliberately forced or picked the lock of the drawer in which you kept the darts and abstracted two of them. Presumably he or she intended to use them for something. The obvious use, you think, is to kill Professor Roseland. But, so far as we know, the Professor died a natural death, and there appears to be no motive for anyone to kill him. What made you think of murder, Mr. Seymour?"

"Why—I suppose it was what that fool Couche said."

"And, when you missed the darts, you immediately associated them with Professor Roseland's death?"

"I— I—" Seymour began incoherently, but Sylvia Roseland intervened, confronting the inspector with blazing eyes.

"This is unfair! It's abominable!" she exclaimed. "You're trying to trap him! You shan't... As a matter of fact, it was I who said that he ought to tell you at once. Wasn't it the right thing to do? Obviously you suspect murder. Why are you here at all if you don't? And, with the darts missing, if—if daddy had been killed that way, you'd have thought Francis had done it."

McCleod bowed before the storm. "Of course," he said. "I wasn't suggesting otherwise than that Mr. Seymour's conduct was perfectly correct. I was merely desirous of getting all the facts... So the darts may have been taken at any time between Wednesday and this afternoon?"

"Yes."

"And you've no suspicion who could have taken them?"

"No. Of course not.... But that wasn't the only reason I came to see you, Inspector. I realise that this brings me more or less under suspicion, if a murder has been committed. But, as I say, I've been researching into this poison, and I know some things about it which no one else in the country can do. That's why it may be possible to clear myself entirely."

"How?"

"It's like this. Immediately on entering the bloodstream, the poison creates a substance which would, by normal methods, be extremely hard to detect, and this is what actually causes death. But there is a simple test which I have discovered, and which has so far proved infallible."

McCleod smiled. "But you must see, Mr. Seymour," he said, "if we were accusing you of murder—and you're the only person who has done that up to date—we could hardly accept a test conducted by you, as the accused, to show the poison wasn't there."

The demonstrator made an impatient gesture and bit his lip.

"Look here," he said in a strained voice. "You may not know anything about science, but it's to be hoped you can understand English... I don't want to make any tests. You'll have a pathologist or someone, presumably. Well, I'll give him specimens of the poison and tell him the method. He can test the method as much as he likes, and judge by results. That's fair enough, isn't it?"

"Why, yes!" McCleod assented. "And we should be very grateful to you. I was only saying just now that if a poison had been used—" He broke off, aware that he had given his suspicions away. The big demonstrator smiled grimly. "And, of course, if the test proved conclusive, and no poison was found, it would relieve your mind of any doubt whether the missing arrows had had anything to do with the death. And if not—"

"If poison were found—" Seymour shrugged. "Well, I wouldn't be any worse off."

"I hope there'll be nothing of the sort," McCleod assured him untruthfully. "Now—"

But Seymour interrupted him. "The point is, that if this test is to be made it's got to be made soon!" he broke in. "The substance which causes death isn't very stable. It breaks up as the body decomposes and once that's happened there's not a trace to show it's ever been there. You've got to hurry!"

McCleod studied him. "And how long—judging by your experiments up to date—will the poison remain detectable?"

"I estimate not more than five days. And three have gone."

"The body will be removed at once for the post-mortem. It seems to me that your best course, Mr. Seymour, would be to write out at once in detail the process which you have described, so that the pathologist may make tests immediately."

"Right. I will."

The demonstrator turned towards the door and went out without another word, but Sylvia Roseland lingered.

"You suspect him!" she accused. "You've no reason to think that—that—he—"

"Miss Roseland," McCleod said soothingly, "believe me there is, at the moment, no probability of our charging Mr. Seymour with the murder of your father. In spite of the sinister interpretation which you both seem to have put on things, we have absolutely no grounds for thinking that Professor Roseland's death was anything but natural. I am sure it has been a great shock to you. But you must see that you are only making things worse by imagining things of this sort. If you would take my advice, you'll go back to the house and lie down. This—" Unintentionally he glanced towards the crumpled body. "This may make you seriously ill."

The girl looked at him, and her lips quivered. The signs of the strain under which she was labouring were evident.

"Yes, I'll do as you say," she said after a pause, and turned to go. But in the doorway she turned. "But you don't suspect him? You don't?" she begged.

"No more than anyone else," McCleod lied. "And you mustn't worry."

Sylvia Roseland's face lit up with hope; but her eyes searched his face. Suddenly she clenched her hands in a despairing gesture.

"I don't—I can't believe you!" she said, and went out.

They waited for a moment, then McCleod nodded to Ambrose and jerked his head towards the door. The sergeant closed it gently.

"Lock it, for God's sake!" McCleod exploded. "We don't want any more breaking in... And now, Superintendent, what d'you make of that?"

"He did what an honest man would have done, coming to us," Carbis conceded reluctantly.

"Too honest to be honest!" McCleod growled. "Well. Let's finish off here before anything else happens."

---

CHAPTER VI
Unwilling Sleuth

THAT afternoon the staff and students of the Juliot Research Institute provided an excellent example of the unnerving effect exercised by the police even upon the most innocent and law-abiding of men. Danton was experiencing the emotions aroused by their presence to a marked degree. After the events of the morning, with the shattered test tube upon his scientific conscience, he would scarcely have been in a mood for work in any case; but the knowledge that he would shortly have to undergo an examination by the detectives in preparation for the inquest produced an intolerable restlessness which made the laboratory unendurable.

To most men there is a sedative influence in the work upon which they are normally engaged; and in the hopes of benefiting by it Danton set himself in a spirit of repentance to repeat the successful experiment. He had broken a flask and two pieces of tubing, besides cutting his finger slightly before he abandoned the attempt as hopeless. But he had to wait there. In his desperation, it occurred to him that he had companions in misfortune. Somewhere in the building, Hope, Wiedermann and Thursden were presumably in a similar state of expectancy, and in all probability discussing the events of the morning.

Lighting a cigarette, he moved over to the window and stood looking out while he considered the matter. None of the three was of a type with whom he had much inclination to be friendly in the ordinary way; but at that time the company of even the worst specimens of the human race seemed preferable to being alone, and he would at least hear what they were saying. Of course he had nothing to be afraid of; but he felt puzzled and curious. He could not understand why the police so evidently suspected murder, even to the extent of calling in the C.I.D. Couche's outburst, he had felt certain, would have been rejected with the contempt which it warranted; but apparently they had received it seriously. Then what was wrong? As he finished the cigarette he jabbed it viciously into the tin lid which served as an ash-tray and turned towards the door.

In Hope's laboratory he drew a blank; but that was no more than he might have expected. Though he himself generally held aloof, the other three tended to congregate in Wiedermann's room, where any interruption by the Professor had been less likely. He was closing the door behind him when the sound of someone hurrying up the corridor made him wait, looking in the direction of the advancing footsteps. The next moment Seymour emerged from the passage leading to Roseland's room.

Undoubtedly the demonstrator was worried. He was screwing up his eyes in the short-sighted way which meant that he was trying to work something out, and muttering to himself. Without looking round, he turned up the staircase. A few seconds later, Danton heard the slamming of the door above, and the click of a lock. Evidently Seymour had gone into his room and locked the door.

Danton stood there for a moment considering. The obvious agitation of the demonstrator was surprising, and he found himself wondering what it meant. Seymour had apparently come from Roseland's room, where the police were presumably in occupation. It looked as though something in his examination by the detectives had caused his excitement. Danton smiled a little grimly. It was poetic justice if suspicion fell on the very man who had been chiefly responsible for spreading the idea of the murder, and the fright might teach Seymour to be less officious. Then the thought of what it might mean for the girl, coming on top of her father's death, sobered him abruptly. Unreasonably, in view of the fact that a few hours previously he had been scarcely aware of her existence, he found himself resenting the engagement. He had known that Roseland had a daughter; but so far as he had thought of her at all, it had been as a figureless, bespectacled blue-stocking. The reality had come as a shock to him.

With the irritable thought that it was no business of his he started slowly along the corridor. He had reached the staircase and was on the point of going up when he heard someone else coming from the direction of Roseland's room. Curiosity made him pause for a moment to see who it might be; and, too late, the lightness of the footsteps enlightened him as to their owner's identity. He would have escaped, but before he could make a move to do so, Sylvia Roseland emerged into the hall. Her face was as white as paper and she had evidently been crying. Although she was no more than a couple of yards away she did not seem to have noticed his presence. Almost opposite where he stood she stopped, put a hand to her eyes and swayed dizzily. Danton sprang forward just in time to catch her as she fell.

He stood there stupidly for a few seconds, supporting her in his arms. Her eyes were closed and she had obviously fainted, but exactly what he ought to do about it was beyond him. The obvious course seemed to be to carry her to the lodge and summon more competent assistance. He was on the point of putting the idea into practice when her eyelids flickered and opened. She stared up at him unseeingly for an instant.

"Francis!" she said weakly; then, as her senses came back to her: "Oh!"

By an effort she hastily disengaged herself from his arms and stood upright. The warm colour flooded her face and as quickly passed.

"I thought—I thought—" she began.

"I'm afraid you fainted, Miss Roseland," Danton said obviously. "You're better?"

"I'm—I'm all right!" Even as she spoke, she had to clutch at the banisters to save herself from fallings "This—all that has happened—"

"I think you'd better lie down," Danton suggested.

"I imagine you're feeling the strain... Should I look for Mr. Seymour? I believe he's just gone upstairs."

"No! No! Not now... We mustn't—we mustn't disturb him."

"Then I think you had certainly better go back to the house... Can I get you a drink of water?"

She shook her head. To his surprise and irritation, the ghost of a smile flickered about her lips.

"I don't want anything.... Yes, I'll go back—"

"Then you'd better take my arm. There's no sense in falling again."

She obeyed the ungracious invitation meekly, and in silence they passed through the door and descended the steps outside. The fresh air seemed to revive her.

"I—I have to thank you, Mr. Danton," she said after a while. "You just caught me in time! It was silly of me—"

"Naturally this has been a shock to you," Danton said, with a formality which he himself felt was slightly ridiculous. "I should see a doctor as soon as possible—"

"I'm not really like this." There was a trace of resentment in her voice. "Only I've just finished taking my finals, and I suppose I'm rather run down. And then this morning—"

Danton nodded sympathetically. He felt that he ought to say something, but whenever he made any effort, the words emerged like something out of a conversation phrase book.

"It—it's not only daddy's dying like that," she went on after a long pause. "They think—the police—that Francis killed him!"

"What!"

Danton was frankly amazed. If he had no great affection for the demonstrator, he had certainly never pictured him as a murderer. Besides, the whole idea was ridiculous, so obviously born in the imagination of an overstrained brain. He smiled.

"Really, Miss Roseland, you mustn't imagine things!" he said. "That's absurd... Of course the police always have to investigate sudden deaths, in case an inquest is necessary, and I admit that they're a little terrifying. I'm frightened myself! But murder—"

"Do they always call in Scotland Yard?"

"Why—no," Danton admitted reluctantly. "I'm inclined to think that that's that ass Couche with all his wild talk about things. It's made them a bit excited, but there's nothing in it."

"You don't understand... You know that Francis is working on that arrow poison? As a matter of fact, you were with him last Wednesday when he was counting the darts, weren't you?"

There was a peculiar note in her voice which he did not understand. He nodded assent.

"Well, he counted them again to-day. Two have been stolen."

"Stolen?"

"They are missing... Of course, Francis is innocent; but don't you see, if—if daddy had been—killed—like that, they'd be bound to think that he'd done it?"

"But he wasn't even here—"

"But can he prove it?" They had almost reached the door, but she stopped for a moment, looking straight at him. "How often could an innocent person prove where he or she had been two or three days ago? Could you yourself? Last Friday?"

Danton stared at her in bewilderment. "Why, I don't know," he admitted. "Let's see... I'd been working in the lab all day and was feeling pretty stale. I had tea in the town, looked back to see how things were going on—that would be about—about half-past five. Then I chucked work for the day and went out for a walk along the Downs. It was a lovely night, with a full moon... I suppose I got back about eight, had some supper in my digs, read a bit and went to bed."

"But you couldn't prove it. Did you meet anyone?"

"Well, I met Thursden coming away from the lab as I was going in... No, I didn't see anyone else, until I got back to my digs. My landlady could swear to that."

"Then you've not an alibi yourself!"

There seemed to be a note of triumph in her voice. Danton frowned a little, then smiled.

"I suppose I haven't... So I suppose I'm an alternative suspect?"

"Why not?" She was evidently in deadly earnest. "You—you didn't like my father, did you? None of you did?"

"Why—" Danton hesitated. He was bad at dissimulation, and disinclined to lie. "Really, Miss Roseland—"

"I know you didn't. Francis has spoken to me about it. We quarrelled about it once... And you were there counting the darts. And you can't prove where you were—"

"But—but this is absurd!" Danton said helplessly. "You can't really think—"

"Why shouldn't I? Why shouldn't the police, if it was put to them?" She was looking at him with a sort of fierceness in her eyes, and there was a red spot of colour on each cheek. "Mr. Danton, I know Francis is innocent, but I know that the police suspect him. I can't—I can't do anything for daddy, but I'm going to save him. You've got to help me. You've got to! Or else—"

It took a moment or two for Danton to realise that she was actually threatening him. He felt himself wavering between irritation and amusement; then he reminded himself of the strain under which she must be suffering.

"Well, Miss Roseland," he said with a restraint which somehow made the words sound very cold, "I am quite prepared to account for my actions to the police if necessary. I think that you exaggerate. The police will not wish to charge Mr. Seymour if he is innocent. I should be pleased, of course, to do anything in my power... But if you are threatening—"

He got no further. Unexpectedly she seemed to collapse as her self-control gave way. She covered her face with her hands and sobbed convulsively. Danton gripped her arm.

"Look here," he said, "I'm an ass. I ought to have known that you were absolutely overwrought... You've got to go inside and lie down. I'll find the housekeeper, and she'll see to you. Then I'm ringing for a doctor."

Without resistance she allowed herself to be led inside. Danton was familiar with the house; on various occasions he had suffered there at professorial tea- or dinner-parties. He opened the door of the drawing-room, ushered her inside and led her to a chair. She smiled her thanks a little tearfully.

"Better? That's good... But it doesn't make any difference to the programme. flow shall I find the housekeeper?"

"Mrs. Robertson? She's out. And, really, I am better." She looked at him imploringly. "I couldn't bear to go to bed—"

"If you saw a doctor, he'd give you something—"

She shook her head. "I only want one thing. I want to get this—this horrible suspense off my mind. I want to know—to be able to prove that Francis didn't—couldn't have—" She broke off, and was silent for a moment. "You see, Mr. Danton, I could tell from the manner of the inspector. There is something serious, and they do suspect Francis. And if that's so, time may be important. People forget so soon—"

"But I should have thought Mr. Seymour himself—"

"You don't understand him as I do. He—he's so hopelessly unpractical outside his work. He doesn't seem to see the importance of it. And he can't remember anything..."

Danton frowned. "I don't see what we could do. It seems a little absurd taking a lot of trouble to prove he's innocent before anyone's suggested he's guilty.... Of course, I'd be pleased to do anything... But I don't see what one can do."

"Don't you see? If we could prove his alibi— If we could find people who had seen him, and were prepared to swear to him—"

Danton nodded assent; then the ludicrous side of it occurred to him. "Well, I'm ready!" he said with a smile. "But amateur detective stuff is really outside my line. You're seriously suggesting that we should set up as budding Holmeses—?"

He stopped as he saw the expression on her face. The idea might be laughable, but she appeared to have made up her mind about it. She bit her lip.

"I'm going to," she said. "Whether you help me or not—"

"Oh, of course, I'll help—"

They both turned sharply at the sound of a gentle cough behind them, a stagey, artificial cough of the kind intended to call attention to one's presence. From the depths of the arm-chair which had hidden him, Dr. Boynley was just rising. He advanced towards them, and bowed with an old-world courtesy.

"I have to offer my apologies," he said gravely. "Believe me, I had no intention of eavesdropping. I beg your pardon if..."

Danton found himself flushing. There was something about the position into which he had been forced which made him reluctant to be overheard. But Sylvia Roseland was evidently not similarly embarrassed.

"Why, Uncle, of course not!" She rose to her feet, and put her arm round him. "Besides, we'd like you to help. You see—"

"I owe you the apology, however... I am afraid that, reading the notes for my new volume on Lucretius, I must in some unaccountable way have fallen asleep..."

Danton repressed a smile. He had, on various occasions, been privileged to hear extracts from the work in question, and he was not surprised that it should have a soporific effect even upon its author.

"Never mind, Uncle darling. As I said, you can help us too. And you mustn't think it's stupid—"

"Though not intending to listen, unavoidably I overheard something," Dr. Boynley admitted. "It was most interesting. As I understand it, your suggestion is that you, Sylvia, and Mr. Danton should attempt the elucidation of the mystery—at least so far as concerns the establishment beyond all doubt of Mr. Seymour's innocence. I should be interested to know what models you propose to follow—Lecocq, Sherlock Holmes, the more recent, but infallible, Dr. Thorndyke. That, perhaps, would suit you best, Mr. Danton? The scientific method..."

Sylvia Roseland smiled a little. "I don't know that we'd thought of any of them," she confessed. "My idea was simply to ask questions and find out what really happened..."

"Of course, accurate data are necessary. That is an indispensable preliminary." He frowned and caressed the long white moustache on his upper lip. "Now, let us consider... Our aim, as I understand it, is to establish beyond all doubt that Mr. Seymour left this house to catch the six-thirty train from the station, that he caught it, travelled to London on it, and attended the meeting of the conference that night. If that is certain, his innocence is proved?"

Danton nodded assent. Secretly he was astonished that the old don should display such a knowledge of detective fiction; and equally that he should so readily be prepared to concentrate on what seemed a wild-goose chase.

"We may divide the investigation into three parts," Dr. Boynley pursued equably. "First, at what time did Mr. Seymour leave this house? By whom was he seen? In this connection, I am myself a witness. It was—let me see—about six o'clock, or a few minutes after, when I last saw him. He came in while I sitting in the library with Charles—Professor Roseland—" He saw the quick look of pain on Sylvia's face, and hurried on. "He would then be in good time to catch the train assuming that he walked to the station. I did not see him leave myself, but the maids or Mrs. Robertson may have done so. That, I think, Sylvia, is your province. You can ascertain that more easily than either of us."

"Of course!" Sylvia Roseland answered eagerly. "I can do that."

"Though it is desirable to establish every movement, that is of comparatively small importance. For we know that Professor Roseland did not leave this house until after seven-thirty. If, therefore, Mr. Seymour actually caught the six-thirty train, I think that we could prove he could not have been in the neighbourhood of the house at the time Professor Roseland left, and, if he attended the conference, that he did not return that night."

Danton only nodded again. He felt slightly stunned by the old man's logic.

"Here, there is a point which we can, perhaps, verify without any difficulty. Sylvia, my dear, have you a time-table?"

"In the library..." Sylvia rose to her feet. "I'll get it at once."

"One moment. It will be Mr. Danton's task to establish the fact that Mr. Seymour caught the train. To do this, he will in all probability have to interview railway officials and others to whom Mr. Seymour is not known by name... I wonder if you have also a photograph, my dear, of your fiancé?"

"Yes, darling." She coloured a little. "I'm not sure which is the best—"

"If you would bring them down, we could choose," her uncle suggested. "Now, the time-table—"

He smiled after her affectionately as he watched her go towards the door. As she disappeared, he turned to Danton with something like a twinkle in his eye.

"I am no mind-reader, Mr. Danton, but you will confess that you are a little surprised at my taking part in this?"

"Well, sir—" Danton hesitated, "I must confess that the whole business seems a little far-fetched to me..."

"Very probably. But, believe me, Mr. Danton, it serves its purpose... I have known my niece since she was a child. Like her mother before her, some intense loyalty is an absolute necessity to her. Before, it was to her ideal of her father. Now, it has partially been transferred to the man whom she loves. Her father's death has been a terrible shock to her—so terrible that if she were to allow herself to realise what it implied, it might mean a complete breakdown. I am convinced that we can best counteract its effects by allowing her loyalty to Mr. Seymour full play..."

"I'm inclined to agree," Danton said a little doubtfully. "But isn't it rather an artificial prop—itself rather a strain? When it is removed—"

"My dear Mr. Danton," Dr. Boynley smiled, "after seventy-odd years of life, one comes to realise that, for our preservation, neither joy nor sorrow can remain at too high a pitch. We have only to play for time. If Mr. Seymour is proved innocent—and since there appears to be no evidence against him worth mentioning it seems highly probable that he will be—it will give Sylvia the feeling that she has saved the man she—" He broke off at the sound of the girl's footsteps crossing the hall. "Your task, Mr. Danton," he was saying as she re-entered, "is by no means so difficult as you might imagine. Mr. Seymour is a readily identifiable figure. Apart from his build, dressed, as we know him to have been dressed, in that extraordinary coat and hat which he affects, people must have noticed him..."

"The 'Teddy-bear' coat? It really suits him, Uncle," Sylvia protested. "And the hat..."

"My dear, it is a poor compliment to his appearance to say that clothes suit him when they practically envelop him completely," her uncle rejoined with a suggestion of tartness. "Ah, the photographs. Perhaps you would select one, Mr. Danton... The time-table, Sylvia."

He was flicking over the leaves when Danton accepted the half-dozen photographs which the girl held out. The business of selection was strangely repugnant. It seemed to him that the girl had acquired studies of Seymour looking even more grotesque than usual, and yet, from her expression, it was clear that she thought them wonderful. Discarding snapshots of Seymour bathing, Seymour in flannels, Seymour on the river, Seymour seated in what appeared to be a bower of roses, and Seymour on board ship, he chose one representing him in the objectionable coat and hat, and a studio portrait which, though flattering, was a sufficiently life-like representation of his features.

"These two, I think," he said briefly. "People ought to know from these—"

"I think this one's more like him"—Sylvia held out the bathing snapshot.

"Only he didn't go to the station in a bathing-costume..." Danton said a little irritably. Dr. Boynley fortunately intervened at that moment.

"Yes, as I thought," he announced. "The six-thirty is a non-stop train. If Seymour boarded that he went to London. If he went to London, he could not return here before half-past eight. If, therefore, he was seen at the conference at any time before half-past nine, his alibi is established... You have, perhaps, Mr. Danton, friends who attended the conference?"

"Yes. I think so—and one of them at least knows Seymour."

"That is excellent. And, Sylvia, there is yet another point in which you could assist. Ascertain from Mr. Seymour what kind of ticket he booked—single, return, or week-end; first or third... And that, I think, is all for the present—"

"Uncle, you're marvellous!" Sylvia kissed him, and he smiled down at her.

"My dear, believe me, I have a particular interest in clearing this young man of any suspicion..."

With a start Danton realised the length of time during which he had been away from the laboratory. In all probability Inspector McCleod had long since looked for him, and looked in vain.

"If you'll excuse me—" he asked. "The police probably want to see me—"

"Of course... Show Mr. Danton out, Sylvia. Good afternoon, Mr. Danton. And good luck!"

Neither of them said a word as they went towards the door; but on the step Sylvia stretched out her hand. He took it.

"I—I—" she faltered. "Oh, thank you!"

As she turned abruptly and vanished inside, Danton started back towards the laboratory.

---

CHAPTER VII
Various Evidence

IN the little room opening off the laboratory which he had chosen as his temporary headquarters, McCleod was trying without any conspicuous success to make something coherent of the mass of evidence which had been gathered up to date. Danton need not have worried that he would be missed. In the interviews taken by the superintendent, and in the discoveries which they had just made in the laboratory, McCleod had plenty to occupy his time. As Carbis entered he pushed away the papers from in front of him, and leaning back with a sigh, felt for his pipe.

"Nothing fresh," Carbis announced. "Ambrose has finished trying for prints. There's no more that he can tell you."

McCleod leaned forward and selected a sheet from the pile.

"The fingerprint situation is interesting enough, anyhow," he said. "For one thing, I never saw a finer crop. Of course, that's pretty well what one might have expected. I don't suppose that there's much dusting done in that place in the ordinary way, and the surfaces were as good as one could hope for.... By the way, do you happen to know when the place was cleaned?"

"I asked Couche. He said on Thursday evening. And he was sure, too, that the window hadn't been forced then. So that button was presumably left there after that."

"If he made a good job of it... I don't think we can say the same about all the prints. It's pretty certain that he didn't wipe over all the glasswork. And the prints are interesting. Seen them?"

Carbis shook his head. "Not properly. Haven't had time. But I suppose you haven't got prints to compare yet?"

"Not in all cases. But it's remarkable enough without that. First of all, there are a great many of two kinds of prints, one of which is the Professor's. I think it's practically certain the others are Couche's, but we'll verify that. Those are scattered all over the place. Then there are a good many mixed ones, just in the neighbourhood of the body. I imagine that some of the people who found it touched things without thinking. There's nothing in that. But two really curious things emerge."

"Two?" Carbis asked. "You said something about the apparatus."

"Yes. That's one of them. The apparatus which Roseland is supposed to have been using on the bench shows just one kind of print—rather smeared—the kind I think is made by Couche. There are no others whatsoever. So Roseland didn't put up that apparatus, unless he wore gloves. In fact, either Couche did, which he denies, or whoever put it up used gloves."

"And the other?"

"The other is more remarkable still. Look here."

He moved the papers and gingerly drew towards two of the larger fragments of broken glass which had been found near the body. He pointed to it, and proffered his magnifying-glass.

"They're fairly distinct," he said, "but this might help you to make out the ridge patterns. As you see, they're an unusual type. But the really curious thing about them is that they are the only prints which occur on the glass—and that's the only place where they do occur!"

"Meaning just what?" Carbis frowned through the glass, and looked up. "I don't quite gather."

"Well. We can rule out, I think, the idea that Roseland had been wearing gloves which were removed just before, or after, the time he died. We've found no gloves, except those furry gauntlets in his coat pocket, and there's no evidence he ever worked in them. But Roseland's prints aren't there. The inference is that he didn't touch that particular flask or jar or whatever it was, but that someone else put it there. And, apparently, it wasn't one of those who were present when the body was found—if we're right in thinking that most of them managed to leave samples."

Carbis leant forward a little excitedly. "There's one of those who wouldn't—in the ordinary way," he said. "I noticed that."

"Who?"

"You've got your eye on him already. I mean Mr. John Smith. He was wearing gloves when I first saw him. He kept them on all the time... I suppose he may have taken them off to make his examination, but if so, he put them on again just after."

"It's possible." McCleod's tone was dubious. "But I don't see him making a mistake like that. Two mistakes. Any sensible man would have seen that the prints of the corpse were there."

"Even sensible men make mistakes," Carbis insisted.

"Luckily for us.... But have you really thought about the mistakes which have been made in this case? There are the prints; the obvious forcing of the window, the unused poison dart, the coat button, the sample of cloth, the traces on the underside of the bracket... D'you know, I'm not sure that I can swallow all those."

"Well, of course, they may not all be traces left by the murderer. The button—"

"Might have been left some time during the day? Yes. But it's hard to see who would legitimately force and climb in by the window. It seems to me that these clues provide a picture not of the murderer, but of someone he would like us to suspect. What do they suggest to us about him?"

Carbis had started to reply, but McCleod had asked the question purely rhetorically. He went on:

"They suggest that the murderer was a man wearing a brown-checked tweed coat with green buttons, a big man, who left his fingerprints on the broken glass, but wore gloves to handle the apparatus—and everything else, and who used a poisoned dart of a kind to which only Seymour, and to a more limited extent Danton, had access. Now, if it turns out that Seymour has a brown coat—it might be mixed brown, or a check—that it's got green buttons, one of which is missing, and that those are his finger-prints on the broken glass, we should have a lovely prima facie case against him."

Carbis nodded; but McCleod smiled grimly.

"So lovely that I shouldn't believe it for a minute!" he said. "Of course, he seems to be a pretty muddleheaded sort of an ass—outside his subject; but I can't think that even he would be quite so big a fool. And, in particular, would he have chosen as a way of killing Roseland poisoned arrows not available to anyone else in the country, and then, instead of trying to get it passed off as natural death, actually insist on having it treated as murder?"

Carbis fingered the papers on the desk, and then bent down to select a couple of sheets from the pile. He read them through, and looked again at McCleod.

"Yes," he said. "There's no doubt that he and Couche between them were responsible for our being called in at all. I don't know what O'Connor would have done if he'd been left alone. I imagine that he'd have been content, as a doctor, to make as careful investigations as he could... By the way, there's one clue you've forgotten. That rigmarole on the bench—"

"'Itastuas tariterque'," McCleod murmured. "Yes. And whose is that?"

"I don't know. But I took precautions—including emptying all waste boxes, and I'll swear it isn't the writing of anyone in the laboratory."

McCleod thought for a moment. "Mr. Smith?" he said doubtfully. "And why did he leave it? You see, while it's not impossible that Smith should have made a mistake any more than anyone else, I don't mind saying that my experience goes to show that he's not the man to do anything without a reason, and that he doesn't make many mistakes... I'm sure he wouldn't have left so many traces if the murder had really been like that." He paused; then sat a little more erect, as though something had suddenly occurred to him. "Do you know, I believe I could guess to within two just whose writing that is?"

Carbis grunted. "You're farther than I am, then," he admitted. "And your brown-coated, green-buttoned murderer—"

"Doesn't exist!" McCleod grinned. "That's the sad truth about him. There ain't no sich person!... Where are those statements?"

He reached over for the papers again, and glanced through them before making any further remark.

"They all agree very nicely about what happened when the body was found," he said after an interval. "And from the lot one deduces that Couche, Seymour and the girl thought something was wrong; Danton opposed the idea; Wiedermann wasn't visible; Hope mildly sided with the majority; Mr. Smith did nothing—except be on hand to see someone went to the Professor's room—"

"Isn't that going rather far?" Carbis asked. "He may have beaten you, but he's not supernatural!"

"Well, perhaps it is... And Mr. Thursden, who had been away for the week-end, naturally had nothing to do with it; didn't know a thing and cared less... Ambrose!"

"Sir?"

"Would you mind going to Mr. Thursden—who should, according to his own statement, be on the premises until tea-time—and requesting him, very politely, whether or not he could possibly spare a few minutes of his valuable time to talk to a poor, low-down inspector? You've got to do it very politely, because Mr. Thursden knows the Home Secretary, and Police Commissioner, and will most certainly get you reprimanded or sacked if you're rude to him... D'you feel equal to it?"

Ambrose smiled vaguely. "I think so, sir!" he said. "You want him here, using any necessary force?"

"Good Lord, no!" McCleod answered hastily. His subordinate sometimes misinterpreted his extravagances of speech. "I just want you to ask him nicely. He'll come... And then you might go and relieve the man at the lodge."

Carbis laughed as the sergeant went out. "I wonder what would have happened to you if Ambrose had frog-marched him here?" he asked. "Well, there's nothing wrong with those statements, is there?"

"Nothing at all. That's what bothers me... No one, except his daughter and brother-in-law, and, perhaps, with reservations, Seymour, seems to have loved Roseland... But I don't see anyone had a real motive for murder. We'll have to go a bit deeper into the alibis. Seymour, of course, went to London. Danton was on a long walk across the downs by moonlight—how convenient! Wiedermann went to the pictures—alone? I doubt it!... Mr. Thursden, of course, was staying with the Prime Minister in London... And Mr. Hope spent the evening at his digs—I wonder if his landlady can back him up? Yes, it's all quite natural, but, unfortunately, not so easy to check up."

"You've forgotten Dr. Boynley."

"Oh, no. He, I gather, was in his study, working on some monumental volume which may be published posthumously... By the way, you didn't seem very satisfied with Mrs. Robertson—the housekeeper?"

Carbis hesitated. "I don't suspect her of killing the Professor, or anything like that," he explained. "Only it just struck me that she was hardly being quite frank when I asked, quite casually, whether Roseland had any enemies, and if he'd quarrelled with anyone."

"We'll ask her again. She may remember... And Mr. Smith. His explanation of his actions to you was a model of discretion. He travelled down here by car on Friday night—arriving about nine o'clock—and went to the hotel. Has spent the weekend on holiday, touring round. I wonder? And Couche, as a widower, very properly spent pay-day evening on a sort of mild pub-crawl? I wonder if he plays darts or shove-halfpenny? I might take him on at shove-halfpenny."

"They don't play it down here," Carbis objected. "And which are you interested in, at the moment?"

"I feel I must see Mr. Thursden... And then I've a mild curiosity to learn more about the letters. And I crave a little more information from Mr. Smith—and Mrs. Robertson, since you suspect her—"

"I don't!" Carbis denied indignantly; then saw that McCleod was laughing at him. He was silent for a moment, and then, rather with the air of a conjurer producing a rabbit, said: "You know, I think you said one thing which was wrong, perhaps."

"Good Lord!" McCleod looked at him in astonishment. "Only one thing?"

"You said that this was a murder staged to look like an accident," Carbis went on. "I wonder if that's true? Mightn't it be a suicide staged to look like murder? Or an accident, or natural death? I don't quite see the working out of the idea, but one can't say that the murderer has exactly wrapped things up, can one?"

McCleod digested this for a moment or two in silence. Then he smiled.

"You know, I believe that's rather a profound remark!" he approved. "And I can think of reasons why people should make suicide look like murder, at any rate... You've missed one out, though. You forgot... Look out! Mr. Thursden's coming!"

"I forgot what?" Carbis demanded, ignoring the footsteps approaching down the corridor.

"It might be a murder staged to look like a murder!" McCleod said brilliantly, and looked towards the door as it opened to admit Thursden.

The young man had lost nothing of his self-confidence in the interval since they had met him in the hall. He was smoking a cigarette as he entered, and without invitation seated himself in the chair opposite the desk. McCleod fingered the papers and selected one.

"So sorry to trouble you, Mr. Thursden," he murmured. "Sit down, won't you?—ah, I see you are doing. Excuse me one moment."

He rose to his feet with one sheet of paper in his hand and crossed the room to where the sergeant was waiting. In some bewilderment Carbis noted that it was a perfectly blank sheet. His bewilderment was reflected on the face of Ambrose as he received a few whispered instructions, and went out by the door leading to the laboratory. Thursden's fingers drummed impatiently on his knee while this was happening. When McCleod returned, he was evidently in a mood to stand no nonsense; but the inspector's manner might have soothed anyone.

"Sorry, sir!" he apologised again. "And now, I think, we're ready. Just a few routine questions, Mr. Thursden... You said it was absurd, Mr. Thursden, that Professor Roseland should have been murdered. Why?"

Perhaps it was not the question which Thursden had been expecting. His eyebrows rose, and he hesitated a moment.

"Really, I should say it was obvious!" he said finally. "Who should murder him?"

"You know of no one?"

"I? That's ridiculous!"

"Supposing it wasn't, sir? Has Professor Roseland been worried or depressed? Has he been in poor health?"

"Professor Roseland has been exactly as usual. Really, Inspector, if now that you see the absurdity of the murder theory you're trying to make it suicide—"

"But Professor Roseland is dead, sir," McCleod pointed out mildly. "You last saw him on Friday afternoon, and, I understand, he was then the same as usual... Had he mentioned to you any particular discovery he had made recently?"

Thursden smiled scornfully. "Discovery? I suppose, Inspector, that you suffer from the prevailing delusion that research students are always finding marvellous new elements? Whereas, of course, the fact is that one may work for years—"

He broke off and shrugged his shoulders.

"And none of you ever find out anything? I see, sir." McCleod's eyes were veiled as he looked at the papers before him. "The Professor hadn't made any new discovery, then, sir? I see... You yourself went to London, I believe, before the murder—before Professor Roseland died. On business or pleasure?"

"I don't see..." Thursden began protestingly. "Oh, well! Pleasure."

"By train?"

"By car, of course."

"What time did you reach London, sir?"

"I didn't go straight there." Thursden had apparently resigned himself to the examination. "About seven o'clock, I suppose. I went to the club." He felt for his card-case and extracted a card. "That's the name."

"No doubt there was someone there who would remember you, sir? Just as a matter of form?"

"If you insist on wasting your time, you'd better make inquiries there. Really, I don't know."

"And you didn't get back until this morning, sir? You stayed at the club for the week-end?"

"Of course."

"In fact, sir, you weren't here, and you can think of nothing to tell us at all material to the case?"

"That's just what I've been trying to impress upon you."

"You didn't, by any chance, help the Professor in his experiments?" McCleod looked across the room as Ambrose re-entered and seated himself. I suppose you were often in and out of the Professor's laboratory, sir?"

"Why, I've not been there for weeks!" Thursden said wearily. "I don't understand, Inspector—"

McCleod motioned to the sergeant, who stepped across and handed him a sheet of paper. To the best of Carbis's belief it was the identical piece which the inspector had carried across to Ambrose a few minutes before; but now it was adorned with a set of fingerprints standing out in bold relief. McCleod smiled apologetically as he handed it over to Thursden.

"Of course, I can hardly expect you to know much about fingerprints, sir," he said. "But, you see, these are very distinctive—with that scar running across the thumb. If it was anyone here you might have noticed—"

Thursden took the sheet and examined it. Even he, apparently, was not completely immune from curiosity regarding police investigations. He shook his head and passed it back.

"I've seen nothing like it. And now, Inspector—"

McCleod handed back the paper to the waiting sergeant, and held up his hand as Thursden made a motion to depart.

"Just one or two more questions, please, sir!" he begged. "I won't detain you any longer than necessary... You hardly ever went into the Professor's laboratory, then, sir? Did the other students?"

"You'd better ask them. Not to my knowledge... Of course, they might go in occasionally."

McCleod sighed; then gently pushed forward one of the fragments of glass.

"I don't know if you can form any idea of what this might have been, sir?" he asked. "You see, it's badly broken... But I suppose you would be familiar with it—use it every day, probably—"

"I? Good Lord, no! I'm not interested in gases. You'd better try Wiedermann. I've nothing to do with that."

"The suggestion has been made that Professor Roseland might have discovered a new poison gas," McCleod said hesitantly. "Is there anything you know that bears that out?"

"If you'll pardon me, that's nonsense. Professor Roseland was working upon apomorphine—"

"But it might have been a side-line, sir?"

Thursden disdained to answer, and McCleod sighed again.

"The Professor wasn't exactly popular among the students, was he, sir?" he suggested. "You didn't like him yourself?"

Thursden coloured angrily. "I don't know where you got that impression," he said stiffly. "There was never any disagreement between myself and the Professor."

McCleod glanced across at the sergeant, who had re-entered from the laboratory. His expression changed as Ambrose nodded. He gave a quick glance at the fragments of glass, and his eyes grew brighter.

"So you never use this particular kind of bottle, sir?" he asked gently. "And you've not been into the Professor's laboratory recently? Now, that's really curious!"

"Curious?"

Thursden was obviously indignant; but McCleod was undeterred.

"Yes, curious. I wonder— You may not know, sir, that these fragments were found by Professor Roseland's dead body?"

"Seeing that I've only just arrived—"

"Of course... Well, sir, can you offer any explanation of how it happens they bear your fingerprints—and no one else's?"

There was nothing threatening in the mild voice of the superintendent, but Thursden started as though he had been struck. An expression of incredulous astonishment came over his face, and he paled visibly. For a moment he hesitated, then made an unsuccessful attempt at a contemptuous laugh.

"Absurd!... Oh, I see! A little bluff of yours! Very entertaining—and, I suppose, an example of the way to try to trap people into confessions?"

McCleod motioned to the sergeant. "I'm not exactly trying for confessions yet," he said with partial truth, "all the more since it's not certain if a murder has been committed. But you'll admit it's a remarkable fact which ought to be explained. Have you any explanation to offer, sir?"

"Why, you haven't even got my fingerprints—"

McCleod took the paper from Ambrose. "You gave us them a minute or two ago," he said. "I should have thought you'd have seen through it, Mr. Thursden. It wasn't likely you'd recognise those prints, because they're the sergeant's! But you left your own... Can you explain?"

Visibly discomposed, Thursden seemed to be racking his memory. Carbis noted with pleasure that his manner had undergone a marked change. His voice was distinctly subdued when he finally answered.

"I—I can't think of anything... It's not possible that you believe—"

"I'm just trying to understand the facts... Have you, say, had any glass of that description in your lab? Could it have been taken from there?"

"There's been nothing of the kind there for months. I can't think how... Can't fingerprints be faked?"

McCleod nodded. "They can. But more often they're not. Now, I think that's all, Mr. Thursden. Only I'd like you to try and think when you might have touched anything like that, and left your prints unconsciously... You see, you didn't realise you'd left your prints on the paper... Think it over. Thank you. Good afternoon!"

Carbis laughed as the door closed behind their victim.

"That knocked some of the stuffing out of him, anyhow!" he said; then the smile faded from his face. "But what do you make of it?"

"I don't know—yet. I've an idea—I think we'd better have a word or two with Couche. I'd like to know more about those letters. Get him, Sergeant, will you?"

There was a brief silence after Ambrose had gone. Carbis sat frowning at the glass. He spoke half to himself.

"Seymour's poison darts, Thursden's fingerprints, this gas business for Smith... Good Lord, they're not all guilty?"

"And don't forget the button, the wool, and the mysterious writing... I'm open to bet that I know who we can trace those to."

Carbis looked his question.

"My idea is that we'll find a distinct connection between those clues and Hope, Danton and Wiedermann!" He paused thoughtfully. "And there might be something in that syndicate idea, when you come to think of it. After all, so far as we know, they've all got the same reason for disliking Roseland. And there have been such things—"

The entrance of the attendant interrupted him. Couche came forward nervously, and seated himself in obedience to McCleod's gesture.

"There are just one or two things I'd like to ask. Those letters you found... Would you describe them as closely as possible?"

"Well, sir, they were just an ordinary size—about the same as that, or a little smaller." He indicated the sheet of typing-paper on which Thursden's fingerprints had been taken. "About half a page each, sir—with the crown at the top—"

"Typewritten?"

"Yes, sir."

"From what address?"

"Don't know, sir. You see, they were torn and crumpled as though the Professor had been going to throw them away... That's why I looked, to make sure—"

"Naturally. The address was gone in each case—or hadn't it been written?"

"It had been torn off, sir. Perhaps the Professor wanted to keep it." He paused; then his face cleared. "But they were signed, sir. Clibbens was the name. And after it there were some letters and numbers. I don't remember all, but they ended 'M.I.5'. That's Secret Service, sir."

"Ah! Clibbens?" Carbis asked thoughtfully. "Now, I've an idea—"

McCleod broke in hastily. "Can you remember anything more about the contents?"

"No, sir."

McCleod nodded slowly. When he spoke again after a pause he had changed his ground.

"You wouldn't say that Professor Roseland was popular with the students?"

"Well, sir..." Couche hesitated. "They never said anything to me—" McCleod waited as he broke off. "But I couldn't help overhearing things at times. No, sir, he wasn't. Not with any of them—I mean the students."

"Not Mr. Seymour?"

"Well, sir, he was going to marry Miss Roseland—"

"You knew that?"

"I happened to see a letter—" Couche began uncomfortably. "Very friendly, it seemed, sir."

"Were the students friendly among themselves? Any particularly bad rows?"

"No rows, sir. I'd say Mr. Hope, Mr. Wiedermann and Mr. Thursden got on all right. Mr. Danton seemed to keep himself to himself more, if you know what I mean. Not that there was anything to take hold of."

McCleod thought again; then glanced at his watch. "That's all for the present... Oh, wait a moment. Did any of the students wear brown tweed—probably a fawn with a darker check?"

The effect of his question surprised him. Couche had suddenly turned as white as a sheet. He swallowed once or twice.

"I—I can't call it to mind, sir... They wear their overalls in the labs, sir, mostly."

"You're sure?" McCleod eyed him fixedly. "You'd better tell us if you know."

"I can't tell what I don't know, sir." There was a dogged note in his voice. "I can't remember, sir."

"Right," McCleod said briskly. "That's all, then... Ambrose, you might take a spell at the lodge. And bring me Mr. Danton in about half an hour."

Carbis's gaze followed them out of the door. "He was lying," he decided as it closed. "Hey?"

"He was—certainly about the coat... And the letters? They're a funny business. Of course, I wouldn't say that the Secret Service mightn't be off its head, but... That name meant something to you? What was it?"

Carbis frowned. "The trouble is, I can't be sure," he said. "I only know I've seen it somewhere, sometime, and it seems to me in an official connection... That's all."

"We can at any rate inquire for Mr. Clibbens from the powers that be... And while we're on this, I think we might dispose of someone else... How about running down to see Mr. Smith?"

---

CHAPTER VIII
One Alibi

FOR Danton the return to the laboratory might well have been an anti-climax. So far from the place being thronged with anxious policemen searching for him everywhere, there was not even one in sight, and no sign that his presence or absence there was a matter of concern to anyone. In the entrance hall he hesitated for a moment, wondering whether to go in search of the other students or to return to his own room. The thought of the investigation to which he had committed himself decided him. A certain amount towards establishing Seymour's alibi could be done by telephone, and he decided to do it.

He thought for a moment or two before he lifted the receiver from the hook. Among his friends in London, he decided, Bryanstone was the man most likely to attend the conference; and, in addition, he knew Seymour by sight. With any luck, it should be possible to get him on the 'phone, and it was at least worth while trying him first. As the click of the receiver being taken off told him that he was through to the lodge, he gave the number at once; and thereby remained in happy ignorance of the fact that the connecting link between his extension and trunks was, not Couche, but Sergeant Ambrose, who had been engaged in listening-in to all calls connected with the laboratory for an hour.

"Yes? Who's that? Oh, you, Danton! Why, I thought—"

"That's Bryanstone, isn't it? Yes, Danton... Oh. Yes... There is a certain amount of excitement. The place is simply buzzing with flat-footed policemen—though they seem to have gone to earth at the moment... A good riddance? Don't forget—'De mortuis—' No, I didn't murder him, of course... No, I never felt that... Don't believe he was murdered at all. It's a Press stunt... Oh, Couche is off his head—he'd got a weak heart.... I say, you went to the conference the old boy was supposed to attend, didn't you? Was he there, by any chance?"

"You mean old Roseland? Not that I saw... Anyway, judging by what the papers say he was dead, and I've not got to the ghost stage yet."

"You may... The papers? What have they to do with it? They were saying he died of heart failure... Oh. They've revised their opinion on that... I meant to have gone to that conference myself, but was too rushed. You went, I gather?... I don't think anyone did from here, barring Seymour. You know Seymour—our Lord High Demonstrator? Didn't see him, I suppose?"

"Seymour?" Bryanstone considered. "The big chap—an ex-oarsman who looks as though he wants glasses? Yes, I did, as a matter of fact... When the lights went up after the first part of the lantern show, and looking as miserable as hell... I don't wonder either, it was a sticky sort of show... Have you been put through it yet?"

"Only by the locals. Just waiting in fear and trembling... We've got two Scotland Yard men here. They may be Sherlock Holmeses—but they don't look it. Particularly the sergeant. I say, what time would that be? When you saw Seymour?"

"Why, I suppose about nine? No, before, I think... What's the idea?"

"Just wondered. Thought he missed his train, and wouldn't be there until late."

"Couldn't have been too late... You're sure you didn't poison him? Trying out your new alkaloid! That would be the stuff. Have you got it yet?"

"Well... No... I'll tell you about that some other time. I don't quite know how I stand—you know how it is.... Shall I see you in town next week—if I'm still at large? That's why I rang you up, really... Tuesday? That's fine. You'll meet the evening train. Right. Good-bye."

It was with a feeling of satisfaction for good work done that he replaced the receiver. Seymour had certainly attended the conference, and he had already one witness to prove it. By itself that would almost have been enough; but there was the solitary disadvantage that Bryanstone had seen the demonstrator only in the neighbourhood of nine. So far as he knew, Seymour did not possess a car; but he might have hired one and, by quick driving, have had time to murder the Professor and motor to town in time. It was therefore desirable to go to the station but, cheered by his good success, he felt sure that someone would have noticed the big man. His cheerfulness was suddenly dashed by a depressing thought. By clearing Seymour he was helping to build up a case in favour of himself as the murderer.

Lighting a cigarette he sat down to think it over, and as he did so his gloom deepened. He told himself repeatedly that the police could not possibly suspect him; and yet, there it was. He had a motive, as much motive, if not more, than the other students. As the girl had pointed out, he himself had been able to provide no alibi for the time in question. He had certainly been in the laboratory that evening, as Thursden could bear witness, and he could not prove that he had left before the hour of Roseland's death. He could not prove where he had been. In the alkaloid, his researches into which were sufficiently well known, as Bryanstone's question had shown, he had one perfect weapon; in the darts, which, looking at it coldly, he might have taken from Seymour's drawer, he had another and either might defy detection by the ordinary doctor.

By the time he had finished the cigarette, he had worked himself up into a state of mind bordering upon nervousness. He almost wished that the inspector could send for him, and get over what loomed worse and worse in his mind as a dangerous ordeal. Already the police seemed to have an excellent prima facie case against him, and they could probably improve upon it, with a little luck. Of course, they could not know that he had made the alkaloid, if he denied it. Then he remembered Smith and the sounds he had heard before his visitor appeared. Had he been there? Had he heard or seen anything? At the thought he glanced automatically down at the waste box, and started a little. Contrary to all custom, it had been cleared.

The fact affected him unpleasantly. There was something horribly mysterious about Mr. Smith, in a mild, unobtrusive way. There was no saying what he knew, or what he would tell. And Danton found little consolation in the fact that he was helping to abolish a false trail which might have led the police astray. The vision of the girl as she had thanked him in the doorway came to his mind comfortingly; but the idea persisted. Innocent men had been hanged on evidence which satisfied a jury although open to a different interpretation. He realised suddenly that he had better continue his detective efforts, not only for the sake of Seymour and Sylvia Roseland, but for his own. Moving over to the door, he stopped for a moment to listen. Wherever the police were, there seemed to be no sign of them, and an idea had just occurred to him. Perhaps, after all, there might be something in Couche's accusation; something which, if investigated, might lead in an entirely new direction. His idea was to see the attendant and try to ascertain on what foundation his suspicion rested; and at that time of day the basement and fire-hole were Couche's normal haunt.

His search proved longer than he had expected. In the fire-hole, in the storerooms, and in the room used as a workshop he drew a blank; but the basement door, leading out on the slope at one side of the buildings was ajar. On the point of going upstairs again, it occurred to him that it might be as well to look there.

The door gave on to a cemented path, separated from the drive leading to Roseland's house by a mournful border sparsely filled with bushes and a few plants. Danton looked up and down it in vain. All at once, as he stood there, he heard from the shrubbery the sound of steel striking on stone. In a moment he had tiptoed across the path and was peering through a gap towards which heavy footprints were clear in the newly dug soil. His brows creased into a perplexed frown as he looked.

He had certainly found Couche, but what the man was doing was beyond him. He had a spade in his hands, and with it was endeavouring, with poor success, to excavate a hole in the flinty soil, at this point only a few inches deep above the underlying chalk. It was not gardening, as Danton understood it; it looked more as though he had intended to bury something. And then, by the side of an evergreen shrub, Danton saw the parcel. It was roughly wrapped, tied with a single piece of string in a covering of newspaper; and from its indeterminate shape might have been anything. From the way the sides bulged it looked as though it might be something soft. Couche seemed to despair of the results his labours were producing on the chalk. He stood erect, and wiped the perspiration from his face. On a sudden impulse, Danton called to him.

"Couche!"

The effect of the word was remarkable. The attendant jumped round as though he had been shot, flinging the spade away from him. He stared towards where Danton stood with eyes which seemed full of terror; then, as he saw who it was, his face cleared a little. He struggled for self-control.

"Beg your pardon, sir! You startled me, Mr. Danton... Yes, sir? You wanted something?"

"What on earth are you doing?" Danton demanded. "What's that?"

Couche hesitated. "Burning rubbish, sir—I mean, sir, burying what won't burn. What I can, I put in the furnace, sir, but some of the stuff doesn't suit, so from time to time—"

He had been speaking rapidly, with an inexplicable nervousness. Abruptly he broke off, as though wondering how Danton would receive the explanation. Danton glanced towards the parcel.

"You wrap it up first?"

"Just for tidiness, until I bury it, sir... You wanted me?"

"I just wanted to ask you something—and now I just want to ask something else... What is in that parcel?"

"I've told you, sir." Couche faced him determinedly, but there was a desperate look in his eye. "If you've any complaint to make, sir, you'd better go to Mr. Seymour. I'm sure he wouldn't object, sir."

Danton hesitated. After all, he had no business to interfere with Couche. The attendant was standing resolutely between him and the parcel. If Couche were the murderer, he might not scruple at a second killing; and if he were not, Danton would not be justified in knocking him out. Besides, to push matters to a head would mean that he would have no hope of finding out what he had come to ask. Too late, he wished that he had said nothing, but had let Couche finish, coming back later to disinter whatever he had buried. The next best thing seemed to be to pretend that he was unsuspicious.

"Why, of course I've no complaint," he said. "Just curious... As a matter of fact, my whole reason for coming here was curiosity. Couche, what on earth made you say that about Professor Roseland being murdered? And who did you think murdered him?"

He put his hand in his pocket, and jingled some coins together suggestively, but the attendant only stood scowling.

"I'm saying nothing, sir," he answered after a pause. "I've got enough trouble as it is through speaking, bothered by the police this way and by those reporter fellows that way. I tell you, sir, I wish I'd never spoken about the letters—"

"Oh. You saw some letters threatening Professor Roseland?"

"Not threatening him, sir; saying about his new gas, and how the spies would be after it—"

All at once he seemed to realise that he had, in fact, already given away the bulk of the information he possessed. The words died on his lips, and he looked at Danton blankly.

"Oh," Danton said thoughtfully. "Roseland had had letters warning him of spies? And he'd invented a new gas. Now, look here, Couche. You might as well tell the rest. Who sent them?"

"Don't say I told you, sir, for the Lord's sake... Mr. Seymour was on to me a few days ago about this very business—looking at letters and so on, sir, and he questioned me pretty strict—though not about those, sir, you understand. And the superintendent warned me—"

"I'll say nothing to Mr. Seymour—if you tell me the rest. Who sent them?"

"Government letters, they were, sir—from a man called Clibbens. They'd got the crown at the top. They talked about his new poison gas, spoke of an interview this week-end, and warned him of enemy agents, sir."

There was a glibness about all this which almost made Danton distrust it. Then it occurred to him that, in all probability, Couche had already recited the story several times to the police. He selected a coin by touch and handed it over.

"That's all? Sure?"

"Yes, sir. And you won't—"

"I won't tell. And you needn't mention that you told me, for that matter."

"No, sir," the attendant assented civilly enough; but the moment he had said the words Danton realised his error. The man was eyeing him queerly, and there seemed to be a question trembling on the tip of his tongue. "Though, sir—"

Danton forestalled him. "Right, then—I won't interfere with a busy man's labours. Get back to your digging."

As he spoke, he pointed towards the brown-paper parcel. The result was all that he could have wished. Couche seemed at once to want nothing but to be rid of him. His next words, Danton guessed, were intended to speed the parting guest.

"Oh, sir. The sergeant—that detective chap, was asking for you a little while ago. You've seen him sir?"

"Not yet. Thanks, Couche."

Danton nodded, crossed the path and re-entered the building, pushing the door to behind him. He walked a few steps noisily along the corridor towards the stairs; then, on tiptoe, passed them and gained the door of the further storeroom at the far end.

Ambrose might be as urgent as he pleased; but having waited so long, he could wait a few minutes more. He was in no mood to leave the mysterious activities of the attendant so easily. The idea which had come to him was simple. Having been caught there, Couche was not likely to pursue his task if it had any specially sinister meaning. He would hide the parcel and try again later in some place where he would not be under observation.

A minute later his theory received its justification. The door opened, and Couche came in, carrying both spade and parcel. He glanced from side to side as though fearing to be seen, and going as far as the foot of the stairs, stood there listening. Apparently reassured, he retraced his steps to the door of what Danton knew to be the fire-hole. Then the spade clanged on the hard floor, and a lighter, more muffled thud seemed to suggest that the parcel had also been thrown down. Danton listened. He had no means of looking into the fire-hole without showing himself, and that, from several points of view, appealed to him in no way. But the sounds which reached him were puzzling. First a vague scraping; then a crumpling of paper as if the parcel was being untied. Once or twice there was the ring of metal; last a curious gurgling sound. Yet it was only with the flaring of the match that Danton understood too late what was happening. There was a mild explosion as the paraffin caught; the glare of flames reflected against the wall. Couche had lit the furnace; and in it, in all probability, the brown-paper parcel was being destroyed to unidentifiable ashes.

Danton hesitated. His first impulse was to rush out and run to the fire-hole. He might yet be in time to save, or at least identify, whatever was being burned. Yet he hung back, aware how curious his own position might appear. Luck was with him. He was still undecided when the matter was settled for him. A bell rang. Then footsteps sounded overhead, and from the stairs came the demonstrator's voice.

"Couche! Are you there? Couche!"

There was a noise as if the furnace door was being closed; then the attendant's voice answered.

"Coming, sir! At once, sir!"

The next moment Couche appeared in the door of the fire-hole. Danton drew back a little as he hurried towards the stairs, but there seemed to be no suspicion in his mind. The next moment he disappeared up the stairs. Danton heard a murmur of voices; then a double tread receding along the passage. In an instant he was racing down towards the fire-hole.

Almost the roar of the flames was enough to show how small his chances were. Couche had evidently been lavish with the oil; for as he seized a fire-bar and flung open the door he was greeted with a burst of flame which made him jump back, shielding his face with his hand. The first outburst subsided a little. Cautiously he approached with the fire-bar ready. Through the flickers he could catch maddening glimpses of something which was not coal or wood; but for a space the heat defied him. A longer bar caught his eye. He snatched it and, going so near that he could feel his eyebrows sizzle, raked with it in the burning mass. He could stand it only for a moment; but as he staggered back something came with the bar, and lay smouldering on the floor.

Danton snatched it eagerly, burning his fingers as he did so. Crushing out the red embers with the sole of his boot, he examined his find curiously, not without bewilderment. It was a piece of brown cloth, an irregular fragment some six inches square, and both from the shape of the hem and the single button which clung to it Danton guessed that it had once formed a part of a pair of trousers.

He stood eyeing it for a few seconds doubtfully; then, crushing the cloth into his pocket, made for the door. Couche might return at any moment, and he had no intention of meeting him again. At the stairfoot he hesitated only for a second, finally deciding on a circuit of the building and an entrance by way of the front door as the more innocent way of gaining his own room. Since he had met no one on the way, his absence would be known only to the attendant, and Couche, probably, had reasons of his own for saying nothing.

In the entrance hall Sergeant Ambrose emerged from the lodge as he came in.

"I was looking for you, sir," he said. "Inspector McCleod asked me to tell you—"

"Right. I'll be along at once. Sorry to keep him waiting."

"No, sir, that wasn't it. He asked me to let you know he couldn't see you just now, and said you needn't wait."

"Oh." Danton was slightly taken back. He did not quite understand this latest development. "Thanks, Sergeant. Then I'll get some tea. I'll be back here afterwards."

But it was not towards a café, but to the railway station that his steps led him. He stopped at the window of the booking-office first, fumbling for the photographs.

"I wondered if a friend of mine travelled on Friday?"

"I shouldn't know—" the clerk began in obvious surprise.

"I've a photograph of him here, as it happens. He'd be travelling by the six-thirty train to town on Friday evening. Do you recognise him?"

The clerk looked at the photograph dubiously. "Not that I remember, sir," he said. "But then, as I said, the odds are against my knowing him."

"Thanks."

Slightly depressed, Danton was making his way towards the gate, hoping for better luck with the ticket-collector when it occurred to him that in all probability he had made a mistake in using the studio portrait. Retracing his steps, he produced the snapshot of Seymour in hat and coat. This time he succeeded.

"Oh, yes, sir. Now I see him with his hat on, I do remember him. Yes, he was here at about twenty past six. He booked a week-end ticket, sir, so he should be back to-night."

"That's what I wondered," Danton said, hoping that he was covering his motives successfully. "You're sure it was he?"

"Yes, sir. I remember perfectly now... You wouldn't be the friend who gave him the dud note, sir?"

"Dud note?"

"Yes, sir. He was very upset when I pointed it out—said a friend had given it to him in exchange for a fiver. That's why I'm so sure."

"No, I'm not guilty there." Danton smiled. "Doesn't sound much of a friend, does it?"

The clerk smiled politely, and Danton started again for the platform entrance with a lighter heart. Having a bad note passed on him might be Seymour's misfortune; but it was distinctly useful as providing an incident of a kind likely to impress itself upon the clerk's memory. Seymour had certainly booked his ticket, and so far all was well. At the ticket-collector's box he produced the snapshot first. This time there was no hesitation when he put the question.

"Yes, sir. I remember your friend. He passed through about ten minutes before the train was due, and then came out again to telephone. As a matter of fact he nearly missed it. The whistle had just gone when he finished, and I nearly had to shut the gate."

"But he caught it?"

"Just, sir. The driver saw him and waited a moment. Not that he ought to have done, strictly speaking—"

"Does that train go right through?"

"Yes, sir. It's the only non-stop train of the day... Oh, thank you, sir."

After all, it had been easier than he thought, Danton reflected as he left the station. He was inclined to congratulate himself upon his diplomacy. He had got the information which he needed, he thought, without arousing any curiosity, and, if necessary, no doubt the guard and driver at least might remember a passenger who had so nearly missed the train. Seymour's muddle-headedness had stood him in good stead on that occasion. He was almost inclined to envy the demonstrator his alibi; for he himself, if the police decided to investigate his movements, could not hope to produce anything so conclusive.

He stopped for a moment in the shelter of the telephone box to light a cigarette, just as the 5.46 down train thundered into the station. Throwing the match away, he stood there doubtfully. Now that he had achieved his object, he was by no means sure what use he ought to make of the information which he had gathered. He could, of course, go straight to the police and give them the necessary confirmation of Seymour's movements. But up to date the demonstrator had not been charged with the murder. The idea of him as a suspect seemed to have originated only in Sylvia Roseland's imagination, and the police questions, so far as he was concerned, did not indicate any great degree of suspicion in that direction. To go to McCleod and explain that he had been doing a little amateur detective work might be to risk a snub. On the whole, since Seymour was now safe, it might be as well simply to reassure the girl, and wait to see if there was any necessity for an alibi before revealing what he had discovered.

He had just reached that conclusion as the passengers from the train began to pass through the gate. All at once a familiar name in a woman's voice made him look up sharply, wondering whether he had heard correctly. The ticket-collector's answer put the matter beyond all doubt.

"Juliot Research Institute, ma'am? Turn right, then left, and you'll see it half-way up the hill in front of you. Big white place—you can't miss it."

Looking at the woman who had asked to be directed, Danton experienced a shock of surprise. Heavily made up and flashily dressed, she seemed about the last type to have any business in any respectable laboratory. As she thanked the ticket-collector, a voice in which affected refinement only partly concealed a marked Cockney accent confirmed the impression given by her appearance, and Danton would have been prepared to swear that her golden hair owed more to art than Nature. She glanced in his direction as she passed, and her expression puzzled him. If anything, it seemed to convey a reckless determination blended with unhappiness.

She had disappeared through the doorway of the booking-office while he was still wondering what could possibly be the reason for her inquiry about the Institute. Thursden and Wiedermann, he knew, were "womanisers" to an extent which he himself did not approve, and his first thought was that their sins were finding them out. Then another possibility occurred to him. It seemed not improbable that the woman's visit might have some connection with the death of the Professor, though what it might be was beyond speculation. He hesitated. His inquiries regarding Seymour's movements had roused in him a detective instinct which lurks in most people, and his own position with regard to the tragedy at least served as a justification for curiosity. On a sudden impulse he hurried to the door and looked out. She was still in sight, walking briskly, and just on the point of turning from the station approach into the main road. As she disappeared round the corner, Danton started to run up the hill after her.

---

CHAPTER IX
The Mysterious Mr. Smith

IT was not to the old coaching inn in the main street which was the chief rendezvous of tourists, but to a less pretentious hotel in a back street that Carbis turned the car when they reached the town. It had been a silent drive. McCleod sat frowning gloomily at the superintendent's side, and said nothing. The superintendent, less depressed by the coming interview with Smith, began to feel the silence oppressive.

"Wonder why he chose this place?" he asked as they swung round into the street. "Shouldn't myself."

"Oh, he'd some good reason. It's not that he's hard up, either. I'd have more excuse myself... Maybe he knew I'd be staying at the other!"

Carbis laughed. "He's not clairvoyant, is he? Why, he booked those rooms on Friday night. You mean he knew the C.I.D. would be called in—that he did the murder?"

"I don't mean anything," McCleod answered sadly. "I don't even know what I'm hoping for. But I know I won't get it."

"You're letting him get you down rather," Carbis suggested. "He doesn't look much."

"No... But you don't know what I suffered from him in the war. I'll tell you one day. I always looked like getting him, and never did. I got people he'd associated with, and got them properly—but I always missed him... I'm not so darned sure that he hasn't got second sight; but he got away every time." McCleod paused for a moment, frowning, but his normally cheerful nature asserted itself. He laughed. "You must have queer ideas about me," he said. "But Smith's my hoodoo."

No one would have guessed from the way the two men ignored the loafer near the hotel door that he was a detective Carbis had had stationed there specially from the time Smith left the laboratory. And McCleod, some judge in these matters, gave the local detective force every credit for an excellent disguise. The man looked, more than anything, like a street bookmaker on the look out for clients.

There was no need for them even to give their names to the porter. Smith was waiting for them in the lobby, and advanced to meet them with a smile of welcome.

"I got your message, Inspector," he said. "I thought of sending you an answer, but—"

It might have been chance that his eyes strayed to the loafer on the kerb, but McCleod would not have sworn it.

"Just a few questions, Mr. Smith," he said, with a suavity which equalled Smith's own. "Is there anywhere where we could be private?"

"Of course. I have made arrangements... If you would come this way—would you care for tea?"

McCleod shook his head, and Smith smiled acquiescence. They followed him obediently into a small room off the lounge, and accepted chairs. McCleod had an unpleasant feeling that he was being interviewed, rather than interviewing a suspect.

"And now, gentlemen?" Smith asked. "The superintendent, I believe, already has my statement?"

"Of course. But, in view of the tragic coincidence between your visit and Professor Roseland's death, I wondered if you would object to going into the circumstances a little more fully?"

McCleod's voice was positively honeyed, but his lips set a little too firmly as he waited for Smith to answer.

"Not the least objection... I met the Professor—as I met you, Inspector—during the war. Some little time ago, about two months, I happened to hear that he was living here, and wrote to him. His reply was most cordial; he invited me to visit him, but at the time I was too busy. This week-end, I found that I had business in this neighbourhood. I wrote to him asking if it would be convenient for me to call. In his reply, he expressed some doubt whether he would be here the whole time, but hoped that he might see me on Friday or Monday—"

"You knew, then, that he was going away?"

"Oh, yes. I ascertained by ringing up, while motoring down here, that I should be too late to see him on Friday. Knowing nothing of his death, I called on Monday morning, and was taken by Mr. Hope and Mr. Danton to his room."

McCleod digested this for a moment in silence.

"You had business here?" he asked. "Would it be impertinent to ask—"

"Impertinent? Not at all." But for the first time a shade of trouble seemed to pass over his face. "My business was, and is, rather private," he said after some slight hesitation. "But I am sure anything I say to you will go no farther—"

McCleod inclined his head. His eyes were brighter, but otherwise he showed no sign.

"Of course," Carbis confirmed.

"I was buying a race-horse," Mr. Smith said simply. "For the Derby."

McCleod shifted the least degree; but Carbis's jaw dropped perceptibly.

"But not from the Professor?" McCleod asked.

"I doubt if Professor Roseland had one," Smith answered with equal gravity. "But, as I said, it is a secret. My aunt would object."

"You need have no fear that we shall disillusion her," McCleod said patiently. "The point is that your visit has been fixed some time; but that you had not seen the Professor for years?"

"Exactly."

"You knew of the Professor's war-time activities?"

Smith smiled, and the smile aggravated McCleod. "Oh, yes. But nothing more recent. About this poison gas, for example—"

"You know about it."

"Everyone has heard of it—now." Smith rose to his feet, stepped across to a table and lifted a heap of newspapers, selecting the top three. "Early editions, Inspector... Have you seen your Press notices?"

McCleod made a wry face. If he glanced at the headlines, it was only while he considered.

"Very sensational," he commented. "Probably more so than the sad reality—that in all probability the Professor's death was natural."

"You think so?" Smith raised his eyebrows a fraction. "Now, that is very interesting... As an amateur, I could scarcely venture to mention a few considerations—"

"I should like to hear them above all things," McCleod assured him with more than a trace of irony. "Any points which occur to you...?"

From a ridiculously feminine-looking case, Smith drew a tiny cigarette and lit it.

"And the first of those," he said slowly, "is the extraordinary complexity of the case from all points of view. Let us suppose a natural death. We have the coincidences of his proposed visit to London, and of my own visit. We have the curious behaviour of the attendant; the remarkable energy of Mr. Seymour; the apprehensions of his daughter. More remarkable still, his doctor is not surprised that he might have been murdered. Granting a natural death, all these must be explained reasonably. For accidental death, or suicide, perhaps the least likely of all, many of the same things apply. In a sense, it seems that, however death took place, someone was determined that it should look like murder."

Carbis glanced across at McCleod, but the inspector scarcely noticed him. He was eyeing Smith with a kind of fascinated interest.

"I said suicide was the least likely," Smith pursued, "but that is only bearing in mind the temperament of Roseland as I remember him. But from two other points of view, suicide might produce a result like this. Suppose Roseland killed himself. There might be good reason if, say, his daughter was a religious type with scruples about self-murder, why he should prefer it to look like murder. Suppose he was heavily insured with a suicide clause in the policy. He might not be able to fake a natural death to satisfy experts; but he might a murder.... And, you notice, the care which has been taken to see that the murder idea was raised."

"Then you reject the idea of murder?" McCleod asked with a trace of sarcasm.

"Not at all. But it is not less confusing than the other... With the case analysed, we had one motive, that of Roseland's unpopularity with the students, for at least four people—or five if Seymour is included. We have another motive in the quarrel with Dr. Boynley, and the violent fanaticism of that excellent old gentleman—"

"What? You know—" Even McCleod was startled.

"I had made a few inquiries on my own account. But I don't think that Dr. Boynley's threat to kill his brother-in-law—"

"Good God!" Carbis exclaimed. "You mean—"

McCleod frowned across at the superintendent and succeeded in stopping him in time.

"I doubt if it is to be taken seriously," Smith went on calmly. "And then, of course, we come to the suspicions which you, my dear sir, are concealing so admirably about me." He smiled, and McCleod shifted uncomfortably. "No doubt," he went on with the air of one making a concession, "your view is reasonable enough. During the war you did me the injustice of suspecting me to be an enemy agent—and, behold, here is Couche saying that Roseland was warned of enemy agents! But an enemy agent needs a motive just like anyone else? Well, here is Roseland's discovery! In the attempt to secure it he was driven to murder... And yet, Inspector, I think that you have not yet found any definite traces of any such a discovery?"

"Our investigations are not completed—" Carbis began. McCleod, who had merely stayed silent, shaking his head in a deprecating way, shot a murderous glance at him.

"But, surely, any memoranda about such an important matter would be found among his more valuable papers? And where would they be? Presumably in his safe—?"

"We haven't been able—" Carbis began, then caught the inspector's eye and stopped.

"Assuming the letters about which Couche speaks are real, and that an 'enemy agent' is responsible. What is the course of events? Let me try to see what I should do myself. But perhaps I am boring you—"

"Not at all!" McCleod said gently. "On the contrary, I am very interested!"

"Well, I learn that Roseland has discovered an important new poison gas—perhaps through the secrecies of some Government department; perhaps he tells me, for we must suppose that we are on good terms, and he has no suspicions. Naturally he is a little elated, wants to confide in someone. I come down, having familiarised myself with the interior arrangements of the laboratory, and the general situation. I ascertain, say, that the Professor is likely to keep such documents in a safe—a reasonable enough Proposition. Not being a sufficiently expert safebreaker"—here even McCleod made a movement, and Smith turned calm eyes upon him for a moment—"I decide to waylay the Professor and get his keys. I force a window in the laboratory and obtain access—"

"How did you know that?" McCleod snapped violently.

"Saw it, Inspector!" Smith answered equably. "I suppose one cultivates a habit of keeping one's mind alert and one's eyes open—in certain professions... To continue. Either there is a scuffle and Professor Roseland falls accidentally, succumbing to his weak heart, or he is killed... I, one must suppose, go at once to the safe through the private door, extract the papers... Did you want to say something, Superintendent?"

Carbis had a struggle with his feelings. "No," he said at last.

"I return to the laboratory and let myself out by the window. And, naturally, I put the papers in a safe place, or dispose of them, and establish as good an alibi as possible by going at once to the hotel!... Sounds most convincing, doesn't it?"

"It does," McCleod said expressionlessly.

"But there are objections. First, as I have said, there is no evidence that I was ever a spy. Secondly, there is only the dubious second-hand evidence of Couche that there was anything for a spy to steal."

He waited, but neither of the two men spoke. McCleod sat biting his lip; then he seemed to realise that he was betraying his feelings and fumbled for a pipe.

"In fact, Couche's assertions regarding the letters, it appears to me, rather point to him as a possible suspect than to anyone else. And we must note that the alleged discovery seems to have remained unknown to Roseland's closest colleagues. Further, you would require to prove, I think, that I was familiar, in a considerable degree, with the movements of Professor Roseland and the working of the laboratory. Assuming I know. Well, it follows that either I have been there, or I have questioned someone—"

"That might have been done through an agent," McCleod pointed out.

"Ah, I had forgotten that I am supposed to have a whole mysterious organisation behind my back. We will leave that. And coming to the next point, does my version of what might have happened when Roseland died explain what was actually found?"

"Does it?" McCleod asked after a slight pause.

"I leave the answer to you—not being fully aware of the nature of your discoveries. To come to the next point. Do I secure the papers? I doubt it—unless they were carried by Professor Roseland. And would he be liable to carry all relative documents? I think not, and consequently, the opening of the safe, if nothing is found, constitutes an argument in my favour. For—as Superintendent Carbis nearly said—I could not open the safe—at least at that time—"

"Good Lord, I said nothing...!" Carbis ejaculated.

"But you were on the point of objecting to that particular statement. Therefore, either the safe has a combination lock—which is the more probable, since you have not yet opened it—or someone else was in the room during the time available. Or perhaps both were true!"

Carbis was looking at the speaker as though he was a ghost. McCleod stared straight before him, puffing at his pipe.

"Further, my actions following the crime are inexplicably foolish. I establish an alibi at the hotel. Why? No one, so far as we can tell, has seen me. Surely my correct procedure would be to establish an alibi as far away from the scene as possible. But, to complicate matters further, here is a schedule of my movements on the night in question. I cannot say how far it can be checked. I might, or might not, have been seen when I telephoned, or stopped for petrol. You would, no doubt, ascertain that. Such as it is, I give it to you."

"You'll sign this?"

"Certainly." Smith produced his fountain-pen and did so, while the other two witnessed. "Well, Inspector? It's all supposition, isn't it? I don't think much of your case!"

"But, surely you ignore one point," McCleod said. "On your account, you didn't get the papers. Therefore, you might have stopped for them... And, I might say, you have forgotten to give me the name of the horse—and its owner!"

"An omission," Smith agreed. He drew a card from his pocket and scribbled two words on it. "And, if you like to step round to Withers' stables, you can see the horse!"

McCleod accepted the card. "Anything more?" he asked.

"About myself? No. About the crime in general—" He paused, and his voice became more serious. "These few points. First, that, in spite of the forced window it has all the marks of an inside job—done by some member of Roseland's family, one or more of the students, a servant, or someone who knew all the circumstances. Secondly, that much depends on the cause of death. If it was heart failure—" He shrugged his shoulders. "If not, was it poison, and what poison? And if no reasonable cause of death can be found, one must suspect an unknown poison—under the circumstances. Which would point to one of the research workers. Say, Mr. Seymour, who is so eager to investigate. Or Mr. Danton, so reluctant to go to the Professor's room, so scornful of murder—who, only a little while previously had said it served some old swine right in my hearing, and shattered a test tube of something in the wastebox—which may not yet have been cleared... Or Couche, who starts the spy scare—"

"You heard and saw that? About Danton? You'd swear to it?"

"When I was looking for the Professor that morning... Now, if there is nothing more, Inspector?"

McCleod hesitated. "No," he said at last. "Not now... You're staying here?"

"For some days, certainly... Then, good afternoon, Inspector. Good afternoon, Superintendent."

Probably both of them would have liked to stop to hear more about the accusation of Danton, but there was at times something almost hypnotic in Smith's urbanity. Carbis, at least, found himself in something of a daze as they stepped into the car. McCleod was looking unusually grim. Feeling that he might be at fault, the superintendent was moved to an apology.

"I suppose I played the fool," he said reluctantly. "Somehow—"

"I doubt if it mattered. Though, at first, I was thinking that we'd told him more than he'd told us... Now, I'm not so sure. There was what he said about Danton... And the things he didn't refer to were interesting. I could almost believe him innocent!"

"That horse—" Carbis began with an air of grievance. McCleod laughed with genuine mirth.

"Now, I'll bet that there is a horse!" he said. "I thought at first this was a mare's nest... There's a horse in it, anyhow."

"What's next? You'll question Danton?"

McCleod considered. "On the whole, I think not... I'm beginning to distrust direct methods of approach. I'd like to think things over.... What I should like you to do is to ring up the Institute and say I'm not interested in seeing Danton just now, and that he can do what he likes. And then, if you could put a man on to tail him—"

"He might do something he thinks needs doing?"

"Yes. It's a good line, often, to give a man rope... If you wouldn't mind doing that, I'll have some tea, and ponder. Drop me in High Street, will you? Near a café."

Choosing an unobtrusive corner seat behind some bedraggled palms, McCleod lingered over his tea, but he did not enjoy it. The interview with Smith had not only exasperated him; it had opened up new possibilities, and he was not yet sure to what they might lead. In spite of the circumstance that Danton had apparently had an opportunity to abstract the darts, he had never been disposed to treat the young man very seriously as a possible suspect. But surely what Smith had told him altered things. On the other hand, the two reasons for suspicion partly cancelled out. If the murderer had used Danton's new poison, he had not used the darts; but he might have taken them to throw suspicion on Seymour.

He had finished his tea, but he lit his pipe and sat there, half turning things over in his mind, and half watching more belated arrivals in the café. Most of the clients were tourists, with a sprinkling of office-workers, and a few more fashionably dressed who in all probability had been shopping. Idly he noted one who did not quite fit in with the scheme of things. The overdressed woman who had just come in and seated herself at a table at the far end of the room was, unless he was greatly mistaken, from London, and not from one of the best parts of London. She looked like an over-aged chorus-girl gone wrong, and McCleod was wondering what she was doing there even before the man who entered immediately after her excited his attention.

McCleod sat a little straighter in his chair; then leaned back behind the protecting leaves of the palm. It was Danton, and, quite obviously, Danton was interested in the overdressed woman. Like McCleod, he had chosen a corner table, but a good deal nearer the door. It was evident that he was guarding the only possible exit; and equally plain, from the frequent glances which he cast up the room, that he was anxious to miss nothing which the woman did.

Here was a new complication. In the state of mind in which his interview with Smith had left him, he would have been interested in anything which Danton did; but he could not place the woman. She might, however, be a clue to the mystery, and Danton's interest alone justified his keeping watch. He had half expected that Danton in turn would be followed by someone identifiable as the watcher whom Carbis should have put on the scent; but there was no sign of anyone at all possible.

The woman seemed unconscious of Danton's presence. She ordered tea, and Danton did likewise. Neither seemed to display much interest in the meal. The woman kept glancing at the clock upon the wall; Danton was evidently fidgeting, wondering how long they were going to stay there, but determined to wait until the woman went. It was growing dark by the time the woman signalled to a waitress and paid her bill. Danton at once did the same; but McCleod was less fortunate. The waitress on Danton's table was the same who had served him. As the woman went out, he had first to wait until Danton had finished; then, exasperatingly, she vanished through a nearby service-door, blind or indifferent to his frantic signals. McCleod did not wait for her. He dashed over to the counter where an elderly, forbidding-looking woman presided, tossed over his card and a two-shilling piece.

"Look here, I can't wait," he said. "As you see, I'm a detective... My table's over there, but my waitress has gone. Pay for it, will you?"

He had dashed out of the place before the look of disapproval on the woman's face had changed to surprise as she read the card. But, brief though the interval had been, it had almost been too long. The street outside was crowded with the town's nearest approach to a rush hour, and, for several valuable seconds, he stood there searching for his quarry in vain.

He would have cursed his own scrupulousness in paying for tea, if that had been what had guided him; but it had not been. Once before, in similar circumstances, he had bolted from a tea-shop, and had ended by losing far more time in explanation than he could ever have done otherwise. He cursed the vanishing waitress who had caused the trouble, mildly and without heat; and glanced up and down the road again. Then his hopes revived. Danton he could not see; no doubt the young man was submerged in the crowd of people hurrying homewards. But the woman's hat was more flamboyant. Far up the street it showed like a beacon, and even as he started after it McCleod realised her destination. She was making for the Institute.

---

CHAPTER X
A Quarrel and a Chase

SYLVIA ROSELAND had spent a miserable hour after the departure of Danton, and the well-meant efforts of her uncle to make her cheerful had a precisely opposite effect. The wave of optimism which had succeeded their planning to establish Seymour's innocence passed abruptly. She had asked in vain whether any servant had seen her father leave the house, or could verify Dr. Boynley's evidence about the time Seymour had set off for his train. The point was of minor significance, if the rest could be proved, but as the one part which she had to play, it had an exaggerated importance in her eyes. She found her mind dwelling reproachfully on her treatment of Danton and the threats she had employed to induce him to undertake a task which had in reality nothing to do with him. After the few words which had passed between them in the morning, she had decided that she disliked him, and felt that any means were justifiable; now, she was less sure.

The arrival of Seymour from the laboratory scarcely mended matters. The demonstrator was gloomy and preoccupied, and it was quite plain that the situation was beginning to prey upon his nerves. For the third time he expounded, with some unnecessary anatomical details, the exact nature of his test, and why it was infallible. Sylvia's self-control snapped.

"Oh, don't! Don't!" she begged. "Can't you understand? I can't bear to think of it... And—and you're talking—talking as if it was just an experiment in the laboratory!"

Seymour wrinkled his forehead. To him, perhaps, that was exactly what it was; except that his own danger gave it an added importance. He subsided for a space into sulky silence, and when he spoke again it was in a different tone.

"I saw you with Danton," he said, though she was too upset to realise the meaning of his tone. "What did he want?"

"He helped me home." She did not notice the implied accusation in the words. "After I left you I fainted—in the hall. He was very kind, and brought me back—"

Seymour was scowling. He did not look at her.

"That didn't take him half an hour," he said. "I was watching from my window. What was he doing here?"

This time his meaning was too obvious to be overlooked. She stared at him in amazement which changed to growing anger.

"Francis!... What do you mean?"

"Only that I don't see what he wants interfering, and hanging round you. First this morning, and then— Well, you needn't encourage him."

"You—you're not implying— Francis, if you think that I should dream—"

"Oh, I didn't mean that. There's no need to take that line. Only it seems a little unnecessary to me.... Besides, it's not right that you should have anything to do with a man—"

"Well?"

The monosyllable might have warned him if he had been in another mood, but as it was, he ignored it. He met her look squarely, and his eyes were as angry as her own.

"If you will have it, with a man who may be your father's murderer!"

She stared at him in wide-eyed horror; and, the blow irreparably given, Seymour repented.

"Sylvia!" he pleaded. "I didn't mean— You mustn't take any notice of me. My nerves are on edge, and I couldn't bear it if—"

"You accuse Mr. Danton of murdering my father?" Her voice was suddenly cold and restrained. "You meant something. What?"

Seymour hesitated. "I've said that I didn't mean anything," he began. "But I don't take the words back. I think Danton's as likely as anyone... If you must know, it's that darts business which gets me. I don't see how anyone else could have taken them. Well, why else should he have done that?"

He paused, but she made no answer. Mistaking her silence for belief, he continued blindly.

"Danton was always bitter about—well, about the way your father ran things. And I'm pretty sure that his experiments were nearing an end. He's a queer chap, and doesn't seem to fit in with the rest. And I'd bet that there's the devil of a temper about him somewhere.... What was he doing on Friday night? I wonder if the police know that?"

"Go on," Sylvia said very softly; but Seymour seemed to grasp his position.

"I don't wish him any harm," he said. "But I don't see what he wants hanging round you. And you can see for yourself with that kind of thing likely to come up against him, it would seem funny if—"

"That kind of thing?" Sylvia echoed in a curious voice. She laughed suddenly, but it was almost a sob. "I suppose, Francis, you've forgotten that an hour ago you were telling me that you yourself were in exactly the same position.... I don't see what you've got against Mr. Danton—unless you do him the honour of being jealous? In that case, I suppose you can't believe in me to the extent of trusting me for half an hour alone?"

"Sylvia." Seymour bowed before the storm. "I'm so worried that I hardly know what I'm saying. I was trying to say I was sorry. Only Danton this morning—"

The appeal to pity might have had its effect if he had been content to leave it alone. She interrupted the excuse harshly.

"Mr. Danton this morning," she said bitterly, "had more consideration for me after knowing me for half an hour than the man who's supposed to be in love with me.... And this afternoon— Do you know what Mr. Danton is doing at this moment?"

Seymour only shook his head surlily.

"I'll tell you. You're doing your best, so far as I can see, to level all kinds of vile accusations against him. He has gone to the station to see if it can be proved that you took that train—with a view to establishing your innocence! If things are as bad for him as you say, so far as I can see, it makes it all the finer. And you—and you—"

Her voice faltered. Seymour stared at her incredulously. He moistened his lips nervously before he spoke.

"He—he's doing that?"

"Yes. He's trying to prove that you went as you say you did—that you were at the conference. And you are trying to make him guilty!"

"At the station?"

There was so curious a note in his voice that her anger abruptly subsided. She gazed at him in bewilderment.

"At the station, of course. And he's got friends who probably went to the conference—"

Seymour sat looking at her; but he seemed to be seeing beyond her. His eyes screwed up in the way which irritated her. At last his face cleared.

"You sent him?" he asked unexpectedly. "You made him do that for me?" He paused. "Sylvia, I'm a fool, but you do love me? Don't you understand that it's because I'm so mad about you that I can't bear even to think of your loving anyone else? Don't you know I'd do anything—anything in the world to prevent things happening to part us? Don't you see?"

The sincerity of the passion in his face overwhelmed her. Her eyes fell before his gaze. She clasped the hand which lay on her knee and her lips trembled.

"Francis, why do you hurt me?" There was no complaint in her voice, but only a bewildered weariness. "I—I do love you. And I do understand how much you love me—and I love you for that too. But sometimes..." She paused, and hurried on as though afraid that her resolution might fail. "Sometimes I wish that you loved me in a different way... Not passionately, not possessively... Only if you could sometimes think how I feel about things a little more..."

She searched his face for some sign of understanding; but she could read nothing of its meaning. There was pain in his voice when he answered.

"I don't know.... Perhaps I should never have loved anyone. Perhaps I think women are different—think on other lines than they do. I've said I'd do anything. If you feel like that..."

The utter desolation of his manner overcame her. She leant towards him, and put a hand on his arm.

"Francis! You mustn't think that... I do love you. I'll try to be as you wish—"

He leant forward, gripping her arms so that the pressure hurt.

"Sylvia, let's end this! I can't bear any more... It's just because of this uncertainty—this so far and no further business of an engagement. If we were married—"

The look on her face was enough. He stopped.

"Francis," she said gently, almost as though she was reasoning with a child, "you know that I'll marry you. Only, you must see, with this hanging over our heads—and—and with daddy just dead—perhaps murdered—"

He released her arms abruptly and, turning his head, looked gloomily out of the window. There was a long silence.

"What difference does it make?" he said slowly after a while. "Your father's death—what people think—if you really love me. We could go away. We could marry quietly—" Abruptly he faced her. "Can't you see that it tortures me—that I can't bear it? Sylvia, I beg you—"

"Please, Francis," she pleaded. "Don't. It can't do any good... I couldn't—"

"Don't you see, as we are, things may always come between us?" He spoke fiercely, quickly. "That's why I'm jealous—unreasonable, perhaps... As I was with Danton. The very thought that you should ask anyone to do things for me—the idea of being indebted—" He made a violent gesture. "Sylvia, I couldn't stand that!"

"But—but it's nothing!" She tried to soothe him. "I didn't realise how you felt... Perhaps he'll do nothing, anyhow... Francis, can't you yourself—"

"Let the police accuse me if they want! I don't care. It doesn't matter what they say—"

"Not even for my sake?"

His anger seemed to vanish. He put a hand to his forehead and sat for a short time in silence. When he spoke, it was almost as though the scene which had just ended had passed from his memory.

"Of course, you're right, Sylvia," he said almost briskly. "I shouldn't neglect anything... As I told you, I had finished writing out about my test. But the inspector seems to be inexplicably absent. There's only that fool of a sergeant there, and he knows nothing. He could only tell me that they'd be back later. Perhaps—-" He glanced at the clock. "Perhaps he's returned already. Would you mind—?"

"If it's urgent—" Sylvia said with simulated reluctance. She felt completely worn out. If he stayed, in their present moods, something else would happen. And the realisation of that brought to her mind a little haunting doubt. If they could not help each other when things were bad... "And oughtn't you to find out about—about your alibi," she went on, and hated herself because she was merely trying to make him stay away longer. "You could 'phone to someone in town—"

"I'll do it at once." Seymour rose to his feet. His face had changed, as though the emotional thunderstorm through which they had just passed had released the tension. "If you won't mind, darling... Of course, your uncle will be here... And Mrs. Robertson."

In spite of herself, she had to bite back a smile. It was so typical of him that he should think Dr. Boynley and Mrs. Robertson efficient substitutes for himself, and a present help in trouble.

"I shall be all right... Good-bye, Francis."

"Good-bye, darling."

His kiss was almost perfunctory, and with a little shock she realised that she was glad it was so. She stood by the window for a long time after he had disappeared down the path, looking out over the plain below where the dusk was already dimming the outlines of the town roofs, and the smoke hung mistily in the still air. In the chaos of her emotions, her mind seemed to be a blank. She could not have told anyone what she was thinking. She came to herself with a start as Mary, the parlourmaid, entered, switching on the lights.

"Oh, I beg your pardon, Miss Sylvia—" The girl looked at her sympathetically. "You're feeling all right, miss? Can I get you anything?"

"Nothing, thank you, Mary... If you'd draw the curtains..."

As they slid across, blotting out the now almost invisible landscape, she came to herself. The maid withdrew, with a backward glance of pity. Sylvia did not notice she had gone. Her mind was suddenly active. Whatever happened, she must, in some way, stop Danton from going any further with his investigation. As it was, Seymour might forget about it; might think that Danton had done nothing. She made up her mind all at once. At all costs she must see him and somehow explain.

Putting on her hat and coat, she was surprised at the urgency which she felt, and she could not deceive herself to the effect that it was on Seymour's behalf. She was only too well aware of his jealousy. She tried to repress the fear that, under the circumstances, it might well be dangerous to Danton.

She had intended to go to the laboratory first, on the chance that Danton would have returned, and with the knowledge that Seymour should for a time be detained at the house by his telephone calls. The journey proved unnecessary. She had reached the point where the way to the house diverged from the main drive when the lights of a car swung down the hill towards her. As it drew level, it stopped, and a voice which she recognised as Hope's called from the darkness.

"Can I drop you anywhere, Miss Roseland?"

Sylvia hesitated. She could not very well say that she was going in search of Danton.

"I wondered if Mr. Seymour was at the laboratory?" she asked, more to gain time than anything else; and then saw an indirect method of approach. "I think he said he was looking for Mr. Danton?"

"Oh. Haven't seen either of them." There was a suggestion of constraint in his voice, as though he was aware of the strained relations between the two men. "I know Danton went out some time ago, and he's not come back."

"Perhaps you might take me to town," Sylvia answered. "If you could drop me by the post office—"

From there it was only a step or two to the street where, as she had ascertained that afternoon, Danton lodged: but she hoped this would not occur to her escort. But Hope seemed to be either nervous or occupied with his own thoughts. He said nothing as he closed the door behind her and restarted the car.

"Will it take you out of your way?" It was merely to break a silence which was becoming oppressive that Sylvia asked the question. "You're not in a hurry?"

"Oh, no. Not at all." He spoke jerkily, and in the voice of a man who is trying to seem at his ease. "I was going that way—"

The silence fell again. Hope's manner was in such marked contrast with his usual loquacity that she found herself asking what it meant. Perhaps it was merely symptomatic of the general atmosphere of tension. At last he himself felt impelled to say something, and his words supplied a more likely explanation.

"Awful shock for you, Miss Roseland," he said a little hesitantly. "Fact is, I don't know how to put these things, but I'm sorry and all that."

Sylvia struggled for something to say. He had raised the one subject which everyone had to talk about in the way which she was trying hardest to avoid. But, once started, he went on as though it was a relief to speak.

"Terrible business. I don't mind saying I can't understand it at all. I mean to say, why there's all this fuss and bother. Makes it all the worse for you, I suppose. But these local chaps must have got hold of something, if they've called in Scotland Yard. That inspector doesn't look a bad fellow, but they make you uncomfortable. As though you wanted to confess all, or something."

"They've interviewed you?"

"Not yet... I suppose they can't do everything at once. But it makes one wonder if they just think you're not worth bothering about, or if they're reserving you as a possible suspect... Of course, the superintendent took a statement. Not that I'd anything to tell him. I was at my digs all the time— I mean, when it happened. My landlady can prove that. Only—"

"Then you're out of it?" Sylvia suggested; but there was a trace of anxiety in his voice which made her doubt it.

"I don't know," Hope said doubtfully. "The superintendent came round to my place—I suppose to have a look round. I thought he gave my window a nasty look. And come to think it over, it would be the easiest thing in the world for me to have got out—" Evidently it occurred to him that this line of conversation was unsuitable, for he stopped a little abruptly. "Puts one off one's work," he added.

"I shouldn't have thought that worried you!" Sylvia's surprise was genuine. Hope had never struck her as a particularly hard-working young man. In fact, she had never understood how he came to be engaged in research at all. "Oh, I didn't mean—"

"Well, you see, I'm not one of those people who like to stew in the lab just for the sake of being there, but, you know, a man's got to work sometimes— Here we are!"

It was a relief to her when the car drew up at the kerb and she stepped out with a word of thanks. The conversation had been a distinct strain, and with her destination almost in sight, she hurried up the turning from the main road, almost running in her eagerness to get her visit over. In the half-darkness, she had some trouble in finding the right number, and, when she did so, the unlighted windows made her heart sink. She knocked and waited, without much hope. After an interval the door opened. A tall, rather gaunt-looking woman peered out.

"I wanted to see Mr. Danton," she said a little timidly. "He lodges here?"

"He might," the landlady answered in a voice which proved her Scottish origin. "You'll be one of those reporter ladies?"

"Oh, no!" Sylvia denied hastily. "My name—my name is Roseland..." Sensing the surprise which she could not see, she hurried to give an excuse. "Mr. Seymour asked me to—" She broke off, uncertainly. "Is Mr. Danton in?"

"No, miss. And he hasn't been since lunch. And me bothered by those—" She peered at Sylvia again, and perhaps noted the weariness which the disappointment accentuated. "Poor young lady," she said with surprising gentleness. "You'd be better in your bed... You'll come in and sit down?"

"No—no thanks... Only, would you give Mr. Danton a message?" On the spur of the moment she found it hard to concoct one which would be understood only by the man for whom it was intended. "Tell him—please tell him—not to go any further in what we discussed. Say—that I thanked him, but that it's unnecessary."

"I will." The woman stood there doubtfully. "You'll be all right on your way home? I'd come with you, but—"

"Oh, no, thank you... Good evening."

Her feet were dragging painfully as she started to retrace her steps. She hoped that Danton would not call to report the results of any investigations which he might have made. If he were to meet Seymour at the house, there would certainly be an unpleasant scene, and she felt that she could stand no more. It was partly to collect her thoughts and partly to steel herself for the gloomy journey up the hillside that she stopped opposite a shop on the corner where the drive leading to the Institute joined the High Street.

For a moment or two she stood there, idly looking at the people who passed the lighted windows on the opposite side of the turning. Then she saw something which for a moment filled her with relief. Danton was standing in a doorway a little way to one side; but the strangeness of his attitude next moment changed her relief to bewilderment. It was quite plain that he was watching someone, and equally so that he did not wish to be seen. There was something curiously stealthy and intent in his attitude, and, on the point of crossing to speak to him, she drew back, and followed the direction of his eyes.

There could be no doubt who was the object of his attention. Although there was a fair sprinkling of passers-by in the main street, the turning to the Institute was deserted except for a solitary figure. She had paused for a moment in the light of the last street lamp before the houses fringing the lane gave out, and was evidently looking at the notice-board opposite, which bore the direction "To the Juliot Research Institute Only. No Thoroughfare." As Sylvia looked, she seemed to have verified her way, and set off. In a moment she was swallowed up in the darkness beyond.

Sylvia looked back to where Danton had been standing. He was still there, but in his manner she seemed to read a double anxiety—not to be left behind on the one hand, and on the other, not to come too near to the woman whom he was watching now that the deserted roadway made his presence more obvious. He waited for nearly a minute; then started up the dark lane and disappeared from sight.

She stood there, divided between eagerness to overtake Danton and uncertainty. His interest in the Woman who had just set out for the Institute puzzled her; and the furtiveness of his movements filled her with misgivings. She felt that she was on the verge of some terrible new mystery involving people whom she knew. It was more desperation than anything else which gave her resolution at last. In turn she started up the hill.

At first she walked quickly. The idea was in her mind to overtake Danton; perhaps to give him her message, perhaps to obtain a solution of the puzzle. She scarcely knew herself. But she had only gone a little way before her pace slackened. She knew Danton only slightly, and had no right to interfere. But more than any nervousness of breaking conventional rules, she felt an incomprehensible dread of what the chase ahead of her might signify. Not very far ahead she could hear the woman's light footsteps on the tarmacadamed surface; but of Danton himself there was no sign. No doubt he was somewhere quite near, deliberately going as quietly as possible, and careful not to betray himself. At the thought she stopped altogether, trying to reassure herself. Of course, her fears were absurd. Perhaps what she had seen was a consequence of the very request which she had made to Danton herself, and he was doing no more than keeping track of a possible suspect. Her fears subsided a little. She was on the point of going on again when a new sound behind made her turn, Someone was coming up the hill behind her.

In a normal state of mind there was nothing in that which would have made her nervous. Now, the invisible follower represented a fresh terror. With a horrified gasp she began to hurry after Danton, preferring anything to the unknown. Almost running, she breasted the first steep slope of the hill; but the sandals which she was wearing made her progress almost noiseless. Lower down, the footsteps seemed to stop for a moment; then come on more quickly. Danton must be somewhere near. Her one thought was to overtake him. A cry trembled on her lips, but she forced herself to be silent.

She was only a yard or two from the white gate which indicated the footpath to the station when, from the blackness ahead, came a sharp exclamation in a woman's voice which made her stop dead in her tracks. For perhaps as long as one could count five she waited, hearing no more than the thunderous beating of her own heart. A curious, choking scream pierced the stillness; then the dull thud of some heavy object falling.

"Mr. Danton! Mr. Danton!"

With the cry she broke into a run, aware as she did so of the heavy footsteps following.

---

CHAPTER XI
Second Murder

SHE had gone only a few steps when a black figure looming against the sky made her stop abruptly. Before she could turn to fly, a hand gripped her. In her terror she cried out. The hold on her was released immediately. She heard a startled exclamation.

"Good God! Miss—!"

Something brushed past her. There was the crack of a sharp impact, then a fall. From her feet came the confused noise of a struggle; she could hear the two men gasping for breath. She stood petrified, hardly knowing whether to run or stay. All at once, from the darkness over her shoulder came a beam of light. To her utter amazement, it focused on the wrestling bodies of Danton and Wiedermann, locked together in a fierce embrace.

"Stay where you are!" McCleod's voice came warningly. "I've got you covered... Let go! Let go, you! Stand up!"

Dishevelled and panting, the two men obeyed. On both their faces there was a look of utter amazement. In the glare of the torch, a red mark showed against Wiedermann's pale face near the chin. For a brief space McCleod evidently looked them over.

"What's this?" he asked. "Who screamed?" For a second he flashed the torch on Sylvia. "Miss Roseland! Was it you?"

"I—I— Only the second time!" Sylvia trembled so that she could hardly articulate the words. "I heard it... Somewhere in front— Something fell! It sounded—"

"Mr. Danton," McCleod snapped. "Can you explain? The woman you were following—whom you watched in the café—"

Danton drew a deep, shuddering breath. He pointed with his hand to the side of the roadway.

"She—she's there, I think," he said hoarsely. "She was standing—near the gate... I couldn't see what happened. She screamed and fell."

He paused, as the shaft of light from the torch swept along the hedge side, coming to a stop as it sought out the still figure of the woman, with the garish hat pathetically askew, half hiding the face.

"Stay where you are!" McCleod commanded. "And don't bolt or—"

He left the threat unfinished and stepping across, bent down over the body, keeping half turned towards them and evidently on the look-out for the least move. Shifting something from his right hand to that which held the torch, he stooped and felt the limp wrist, holding it for a moment as if trying to detect any sign of a pulse. Against the beam of the torch held awkwardly they could see the snub muzzle of an automatic. The light altered its position, concentrating on the face for a moment and moving downwards. All at once he gave a muttered exclamation. The slightest possible movement on the part of Wiedermann made him whirl round at once, snatching the gun into his right hand.

"Stay where you are, I said!" he commanded.

Wiedermann's face, curiously lined with shadow as the light struck it slantingly, seemed to be contorted into a malignant scowl. He ventured a protest.

"Look here, Inspector, what's this?" he demanded. "You can't—"

"What's this?" McCleod echoed sternly. "That's what I'm asking. One thing I can tell you, Mr. Wiedermann. It's murder!"

"Murder!" Danton echoed the word incredulously. "But—but I was quite close— No one came near—"

Perhaps realising how damning the admission was, he broke off. McCleod turned to Wiedermann.

"Well, Mr. Wiedermann? Perhaps you'll explain how you came to be in this?"

"I've nothing to explain—" Wiedermann began angrily, breaking off as the light, flashing in his eyes, focused on the livid mark on his jaw.

"No?" McCleod asked sardonically. "What hit you?"

"I believe—" Danton began.

"Just a minute. I'd like Mr. Wiedermann's version. Well, sir?"

"It's simple enough. I was coming down the hill from the laboratory. Just as I was getting near here, I heard a scream and a fall. Then I heard Miss Roseland's voice calling out Mr. Danton's name. There was a scream. Miss Roseland seemed to be struggling with someone, so I went to help. Something hit me on the jaw, and I was nearly knocked out, but I closed and we went to the ground together. That's all. When you flashed the light, I saw it was Danton."

"The dead woman?"

"I never even saw her. I suppose it was she who cried out the first time.... She must have fallen down by the time I got here. I heard the noise—"

"Go and look!" McCleod ordered. "Do you know her?"

Wiedermann moved over reluctantly. McCleod directed the light only partly towards the face, perhaps so as to keep Danton in view on the edge of its area. It seemed to be a long time that Wiedermann stood there looking down.

"Well?" McCleod asked.

"No. No—I don't—"

"Now you, Mr. Danton.... Step to the left a little Mr. Wiedermann. You know her?"

"No—I don't!" Danton denied. "That is—"

"You were following her? You don't deny that?"

"I was. But that was only—" Danton broke off. "Look here, I can explain everything. But it's a fairly long story. Miss Roseland—"

McCleod broke in. "I was asking you to explain. Why were you following her—if you didn't know her?"

"I was at the station. I went there—well, I'll explain about that later. She came through the barrier off the London train. I heard her ask the collector where the Institute was. I couldn't understand why a woman—well, a woman like that should be going there, and it occurred to me that it might be something to do with the—with Professor Roseland's death. So I followed."

"The London train?" McCleod asked. "That was some time ago. What happened in the meantime?"

"I don't understand it... She was going pretty quickly when she set off from the station. I had to run to get near. All at once she slowed down. By the time we got to the High Street she was just loitering, looking in shop windows and so on. She went into two, and the post office. Then she went into a café. I followed. All at once she got up quite suddenly, and came in this direction... I told you the rest."

There was a brief silence as he ended. McCleod seemed to be digesting the story. When he spoke at last it was to Sylvia, and his voice was more gentle.

"Miss Roseland, have you anything to tell me?"

"I—I—don't know!" Sylvia faltered. I—it was I who sent Mr. Danton to the station—to do something for me. Then I wanted to see him. I went to his rooms, but he was still out. I was coming back—"

She paused. McCleod waited a moment.

"You saw the woman?" he asked.

"Yes."

"And Mr. Danton?"

She hesitated, and the word came almost in a whisper.

"Yes."

"Would you say that he seemed to be following the woman?"

Sylvia was silent. McCleod repeated the question.

"Would you say that he was following—"

"Oh, can't you leave her alone?" Danton asked angrily. "I've said I was following. Isn't that enough?"

McCleod ignored the outburst. "Well, Miss Roseland?"

"Yes," Sylvia whispered.

"And then?" he prompted. "Where was that?"

"At the corner of the turning from the main street... I couldn't understand it, but I wanted to see him particularly. But I didn't know whether I ought to overtake him or not. And—and then it all happened as Mr. Wiedermann said... I heard a little cry first—more an exclamation than anything. Then there was a kind of scream and—and something fell. When I ran forward, someone gripped my arm—it must have been Mr. Danton. When I called out he let go. And there was a fight, and then you came."

"Thank you, Miss Roseland." There was silence again. As a matter of fact, McCleod was wondering what he ought to do next. Danton seemed the obvious suspect; but his story, suspicious as it was, seemed to be partly confirmed by the girl's. And Wiedermann at least was not in so good a position that he could afford to let him out of his sight. Nor was he anxious to leave the body. The obvious course would have been to send her the short distance to the laboratory, where Ambrose was still on duty, but a glimpse of her face in the reflection of the torch made him wonder if she was capable of it. "Miss Roseland," he had begun hesitantly, and then the difficulty solved itself. "Ah!... I wonder who—"

The lights of a car were coming up the hill. The group by one consent had turned to look, and as the headlights swept round the curve they must have presented a sufficiently startling tableau to whoever was driving. Some distance short of where they stood the car stopped abruptly. They heard the door open.

"McCleod!" It was the superintendent's voice, and the inspector breathed a sigh of relief. "What on earth—"

The question died upon his lips as he saw the still figure of the woman in the ditch. He stared from one to the other.

"It's not—" he began.

"It's murder," McCleod said briefly. "She's dead."

"But who— When did it happen? I drove down here not twenty minutes ago, looking for you. I'll swear there wasn't a sign of anything."

"Not five minutes since," McCleod said. "I almost saw it." He glanced towards the car. "Anyone with you?" he asked.

"Yes, I've got a man with me. But he can't drive, if that's what you mean—"

"Perhaps Mr. Wiedermann can?" McCleod asked. "Or—"

"I can drive," Wiedermann said a little sulkily. "If it's any help—"

"That's good. Would you mind going with Miss Roseland and Mr. Danton to the laboratory and waiting there for a short time? Or perhaps the house, if Miss Roseland has no objection?"

Sylvia only shook her head, without speaking.

"But my man—" Carbis asked.

"He'd better go, too," McCleod said quickly. "I'll just explain to him, so that he can give a message to Ambrose—if you don't mind standing by here."

He took the superintendent's consent for granted and moved away, unwilling to say in so many words that he had every reason to see that two at least of the three passengers should remain under supervision. The plain-clothes detective was looking curiously towards the group. McCleod addressed him.

"It's murder," he said. "An unknown woman... Mr. Wiedermann is driving everyone except the superintendent up to the house. I want you to go with them. Bear in mind that both Mr. Wiedermann and Mr. Danton are possible suspects. They might even be dangerous. Take this gun."

The detective was plainly astonished, but he accepted the weapon obediently.

"Mind," McCleod warned him, "you've got to be careful. Suspect the least move... Mr. Wiedermann will be driving, so that leaves you with one to watch. When they get there, wait with them. Send Sergeant Ambrose down to me. After he has 'phoned to the station.... That's all."

Everyone was still standing where he had left them when he returned to the group, and nodded to Carbis.

"That's all right... Now, if you wouldn't mind—"

Danton moved over to where Sylvia stood. She had made no move to accept the inspector's invitation to go.

"May I—can I help you, Miss Roseland?"

But she shrank away from him. "I—I'm all right," she said. "I don't want help—"

Danton bit his lip and fell into the background. With Wiedermann beside her and Carbis escorting him, they proceeded towards the car. McCleod watched them with a frown.

"I wouldn't have thought—" he muttered to himself, and shrugged his shoulders. After all the years of his experience, he reflected, he should have known better than to let sentiment have any place in his work. The car started again up the hill, and Carbis rejoined him.

"What happened?" he asked. "My God! When we were actually on the job—"

"By the way, where was the man who was supposed to be following Danton?" McCleod demanded. "Did Danton shake him off?"

"In a sense, but it may have been accident. Probably was. You see, there's not much cover on the upper part of the lane. Our man took up his position lower down, thinking that Danton would be bound to go this way. But in fact, he seems not to have done—"

From the superintendent's tone he evidently feared some criticism, but McCleod made none.

"Of course," he said. "He went to the station... Listen, this is as far as I've got."

Carbis made no comment as he briefly recounted what had happened. Only at the end he asked:

"You were actually following?"

"Yes—but not near enough. I'd lost them altogether—and then I took a chance on their having come up here. But, you see, I was keeping my distance from Miss Roseland, who was some yards from Danton, and so on. I was nearly out of earshot when she screamed."

Carbis moved across to the body and flashed his torch upon it. McCleod came up behind him.

"But you said murder?" Carbis asked after a lengthy examination. "She's dead all right. But I can't see any sign of violence— Hullo! Here's Ambrose already."

McCleod listened. Certainly someone was coming down the hill, but it seemed to him that the footsteps were slower and lighter than those of Ambrose would have been.

"Is it?" he asked sharply, but in a low voice. "I don't know... Switch out that torch—"

But as the lights vanished the footsteps ceased. McCleod put his lips close to the superintendent's ear and whispered.

"Back to the hedge—and quietly. It may be life and death—"

Carbis started. This view of the situation seemed to him unnecessarily melodramatic.

"But, McCleod—" he protested. "Poisoned darts!"

McCleod barely breathed the words, but Carbis started. There was not a sound as they crept to the hedge and waited, protected on one side at least if it was an enemy who was approaching. McCleod found himself regretting the gun which he had handed to the plain-clothes man. Though by no means a nervous man, there was something in the possibility of the little silent missile coming suddenly which appalled him. He wished that whoever had been coming would make a sound, even the least whisper of a footfall to give a clue to what he was doing. But for more than a minute there was nothing. Evidently the stranger had halted, McCleod decided, for in the stillness even the most cautious movement must have betrayed him.

"Hullo! Hullo! Who's there?"

The voice reassured McCleod. He experienced a wave of relief, and in the reaction felt more than a little ashamed of himself.

"It's all right," he whispered. "It's Boynley."

"Sure?" Carbis asked simply. "And what's he doing?"

McCleod hesitated, with his finger on the button of his torch. It seemed beyond the bounds of possibility that the old don should have anything to do with the murder; but then, it would have seemed impossible for a murder to have taken place under the circumstances at all.

"Hullo! Who's that?"

As Boynley called again, with a kind of querulous insistence, in which McCleod thought he detected a tremor, the inspector made up his mind.

"Superintendent Carbis and Inspector McCleod," he said. "Is that you, Dr. Boynley?"

Carbis made a movement, and McCleod reassured him. "Even if it was, he wouldn't tackle two," he said, and then Dr. Boynley replied:

"Where are you? What's happening? I saw the lights—"

McCleod's torch flashed obediently up the drive. Boynley was coming towards them, coatless and bareheaded, with nervous resolution written in every line of his face. Both men were relieved to see that his hands held no more lethal weapon than an unlighted cigarette.

"This way, Dr. Boynley," McCleod encouraged him. "I'm afraid it's more trouble— Show a light, Carbis!"

The superintendent switched the beam of his own lamp on to the body, while McCleod continued to throw a sufficient light towards the old man. He was near enough now, if his sight had been normal, to have seen what it was, McCleod thought, but he made no sign. It seemed to dawn on him at last what the bundled heap in the ditch was. He started violently.

"Good heavens, Inspector! What—? It's a woman?"

"It's murder, sir," McCleod said grimly. "A bad business, I'm afraid... Didn't you meet the car?"

"The car?" Boynley echoed without comprehension. He appeared to ponder. "I believe a car went towards the house."

"I just sent one of our men up with your niece, Mr. Danton and Mr. Wiedermann," McCleod explained. "They were present when the body was found... Weren't you at the house?"

"Not exactly." Boynley hesitated and glanced nervously down at the dead body. He moved a little farther away towards the middle of the road before continuing. "I was smoking a cigarette in the garden after dinner—or rather, I'd been going to, seeing that it was such a lovely evening. For the time of year, Mr. McCleod, it is really—"

"You were smoking a cigarette?" McCleod recalled him.

"I was about to. In point of fact, I was feeling for my matchbox when I thought I heard something. Then there was a definite scream—and I saw lights down here—"

"So the scream could be heard so far?" McCleod asked. "Yes? And then?"

"Well, it struck me as being unusual, Inspector, so I took a short cut through the garden and came down to investigate. Your lights, of course, guided me towards the place. Besides, I had noted that they had been showing near the tree by the gate. But, when they went out, I must confess that I felt a little nervous. I waited for a little—"

"The car didn't pass you?" McCleod asked.

"No. It was some distance towards the house when I struck the road... Yes, now I come to think of it, there was a car—"

"You heard nothing? Saw no one?" McCleod was trying to form a picture of the garden which he knew ran down one side of the drive. A new idea had occurred to him. He wished that he had made a fuller inspection in the afternoon. "Coming here, I mean?"

"No one," Boynley answered in evident bewilderment. "Who should be there, at this time of night?"

"Why, I suppose some of the members of the household might have been?" McCleod asked. "Mr. Seymour, say."

"I left Mr. Seymour in the house when I came out." Dr. Boynley frowned. "And, if I may venture to make the suggestion, Inspector, you are quite wrong in suspecting Mr. Seymour of any connection—"

"Mr. Seymour?" McCleod echoed in apparent astonishment. He laughed. "Really, Doctor, I hope Miss Roseland hasn't been agitating herself unnecessarily..."

Equivocal though the statement was, it seemed to cheer the old man. He brightened perceptibly.

"I'm glad to hear you say that, Inspector. My niece—" He broke off and shivered a little. "Pardon me," he apologised; "the night air is cool. I have been out longer than my custom—"

"You'd better go back to the house, Doctor," McCleod suggested. "We shall be up there soon—and Miss Roseland might need you. Can you find your way?"

"Oh, yes. I can assure you, Inspector, I am in the habit of walking at night—in the summer, that is... A terrible affair, Inspector.... Murder, you said? You are sure of that?"

"There are indications that way," McCleod said patiently. "But, you'll understand, we're still busy with our investigations."

"Of course. And I mustn't hinder you... I shall see you at the house later."

Although the night must have seemed pitch black after the glare of the torches, he turned quite confidently up the hill. For a little distance they could see him; then he passed beyond the radius of their lamps. But McCleod stood waiting. A few seconds later they heard a gate slam.

"I wonder?" Carbis said half to himself. "Queer that he should turn up like that? And, why couldn't he have—"

"Why couldn't Miss Roseland?" McCleod said a little irritably. "Oh, don't think I'm ruling him out, but there's hardly a shadow of reason—"

"You're forgetting what Smith said," Carbis persisted.

McCleod did not answer for a moment. "Yes, I was," he confessed. "It seems to me we want a heart-to-heart talk with the household staff... Let's get on."

They turned together towards the body. Then something occurred to Carbis.

"But, after all," he said, "I don't see how he could have got near enough and got away."

"He needn't have been near," McCleod answered. "I don't know about his sight, but his hearing's good enough... He might have been able to place her well enough by ear to murder her—"

"By the way," Carbis broke in, "you keep on saying murder—but there are no signs. You never answered my question."

McCleod bent down and pointed to the right wrist of the gloveless hand which lay half opened, as if in a kind of mute appeal.

"Look!" he said simply.

Where the blue veins showed through the white skin a tiny dart of black wood had driven deeply into the flesh.

---

CHAPTER XII
The Green Button

IN the little room off the laboratory which they had adopted as their office, Carbis and McCleod were strenuously endeavouring to extract some meaning from the material which they had gathered in the past two hours. McCleod was busy at the desk, comparing various statements, and considering such evidence as they had acquired about the dead woman's identity. The superintendent had tilted his chair back against a wall, and was frowning as he sucked at a pipe which he did not seem to notice was empty. At last he took it from his lips and broke the long silence.

"Are you going to arrest Danton?"

McCleod looked up, and for a moment stared at him vacantly. Then, very slowly, he shook his head.

"Not while he doesn't bolt," he replied. "It's the last thing I want to do... It's like this. We can say that he'd some sort of motive for Roseland's death, opportunity, and if the medical evidence goes that way, in the poisoned arrows and his alkaloid a way of doing it. But it's all very vague. Is the motive sufficient? If he can't prove he wasn't in the laboratory, can we prove he was? And we're still waiting to know about the poison, which might be the one concrete point. Then, why all these clues pointing to other people, none to him?"

"We had that out before," Carbis rejoined. "That's what any clever murderer might try to do."

"Perhaps; but they're red herrings which might prove effective enough in court. Now there's the murder of the woman. Who is she? From letters in her bag, Mary Alice Ridworth, lodging at an address in Clapham. But who is Mary Alice Ridworth? What's her connection with Roseland's death and Danton? We don't know. Of course, there's opportunity—"

"He'd certainly got that."

"But not exclusive opportunity. Unfortunately, Wiedermann appeared. And then Boynley."

"Boynley wasn't there when—"

"Wasn't where? He says he was fairly near, and, you see, the trouble is this. She was killed by a poisoned dart. Someone might just have come up and stuck it in—or someone might have fired it."

"But it was dark! You couldn't see two yards."

"You're overlooking two things. First, both Danton's account and what I saw indicate that she was keeping an appointment, and, therefore, that someone knew where to look for her. And the second thing is, she wore a wrist watch."

"Wore a wrist watch!" Carbis broke out. "Well, if—"

"With an illuminated dial," McCleod said calmly. "And if you knew where to look, and watched it closely, you could see it at any rate across the roadway, and, by watching the motions, locate the arm. So both Wiedermann and Boynley are theoretically possible."

Carbis gave a kind of grunt which might have been either contempt or reluctant assent.

"With Danton, the position in the second murder is that he's opportunity, possibly means, but no motive known. We'd have to prove some connection between him and the woman."

"Not theoretically."

"But, in practice, nearly always. We've a certain amount of suspicious behaviour, a good deal of circumstantial stuff, but no proof... Where this second murder really helps, up to date, is that it rules out definitely certain people."

"Not enough." Carbis made a grimace. "There are plenty left."

"Be thankful for small mercies. The servants and housekeeper are out of it—though I never thought they were in. More important, so are Hope and Seymour."

"Are you sure of that?" Carbis asked reluctantly.

"Their alibi is as near perfect as possible. For a half-hour before the murder, they were both sitting in Seymour's study at the house, and both the housekeeper and one of the maids confirm it, absolutely ruling out any possible collusion. They didn't move until the news was brought."

"Hope went out earlier."

"Only back to his digs—and, of course, to take Miss Roseland to Danton's. Neither of them could possibly have been present."

Carbis sighed. "It seems a pity," he said. "Once upon a time I really had hopes of Seymour."

"I admit I had myself. But in fact—thanks to Danton!—we know that he couldn't have done Roseland's murder either. And I can't say that I ever suspected Hope."

"There's Thursden, Wiedermann, Couche—and Boynley."

"We'll take Wiedermann first, as the most likely. On Friday night, he went to the pictures, according to his account. Pressed for details, he went with a girl he seems to be running in the town. She confirms it; and the box-office attendant, who knows him pretty well, believes that he went in for the first house, but isn't sure; didn't see him come out. That would rule him out, if one could believe the girl."

"You don't?"

"I wouldn't go so far. But, you see, she might be fond enough of him to do a little perjury; she might be in league with him. I've not been able to shake her, but I can't be sure. It wasn't all at once that Wiedermann mentioned her. He might have fixed it up. To-night, of course, he had no alibi. We can't say how he could have got the dart; but the murder is more in character with what we know of him than anyone else... Suppose he'd had some kind of affair with the woman, and she makes trouble with the Professor... I don't know how far they look after these lads, but Roseland might have done or said something. He kills Roseland; but the woman is still bent on trouble, and this time it means a murder charge. Naturally he kills her."

Carbis considered. "There seem to be a lot of women in his life," he suggested.

"A positive Don Juan, Casanova, or whoever you think is the perfect lady-killer," McCleod agreed. "He's a definite possibility. And then we come to Boynley. For a man who's nearly eighty, a double murder sounds a little spirited—"

Carbis grinned. "There's life in the old dog..." he murmured.

"But still, the second murder needed no particular strength, and he was on the scene of action soon afterwards, as we can testify—"

"If he shot the dart, he'd need a weapon."

"Only a small tube—no more than a pea-shooter. Might only be a few inches long. Of course, we didn't see him carrying one—"

"I wonder?" Carbis interrupted, letting the legs of his chair down sharply. "That unlighted cigarette—?"

McCleod laughed. "You're getting imaginative. Anyway, he could have pocketed it. So he could have done to-night's job. He could have done Friday's, too. He's the only witness of when and how Roseland left. According to him, Roseland just looked into the drawing-room and said words like 'Going now. Be good!'—or something to that effect. But he might have followed Roseland to the laboratory and killed him there."

"No, he couldn't," Carbis objected. "We said it would need a strong man to deal with the corpse and that bar."

"That's true." McCleod frowned a little. "Now we've not gone into this business of the quarrel. We'll do that soon."

"And he's no chemist. And we don't know how he got the dart. And we can't show that he ever knew this woman."

"We've only been working a few hours. All things considered, we've found plenty... There remain Thursden, Couche and Smith."

"Good heavens!" Carbis exclaimed. "I quite forgot Smith!"

"He doesn't come in the same category, of course. He's the sole outsider—who may romp home. Now, Thursden we've nothing against, except those prints. For Friday, he's got an alibi of sorts, because they checked it up in town. Ambrose gave it me a little while ago. Those prints could have been planted. I'm inclined to think they were. I think we'll leave out Thursden for the present, anyhow. There's Couche and Smith—and here I suggest that the most likely thing is that they really did co-operate, if either of them was concerned at all. Couche could supply the inside knowledge; Smith do the various jobs, or put him up to do them."

Carbis shook his head in dissent. "That won't work," he said. "In that case, why should Couche have let out all that stuff about gas and spies and so on? He's the only person who's said anything about that, and, incidentally, it's our only real reason for suspecting Smith."

McCleod opened his mouth to reply, but did not. He considered for a moment, and then frowned.

"That's perfectly true," he said. "I ought to have thought of it... Well, perhaps Couche was an innocent accomplice, if you know what I mean. He gave the information, but didn't know what it was for."

"By the way," Carbis suddenly remembered. "I meant to have told you. I checked the story of his little pub-crawl. It's inconclusive. He seems to have gone to the places he said, but—"

"Well?"

"They can't really swear to times. They know he was there 'about half an hour, somewhere about seven', 'just looked in at six', and so on. What's worse..." He tapped his pipe against the chair edge. "We've not found him to-night at all!"

"Merry-making again?" McCleod asked, and then was silent for a time. "And Smith managed to shake your man—"

"Got out through a back way," Carbis said defensively. "We'd no idea—"

"But he had!" McCleod exploded. "And that's why he chose that damned little hotel!"

After the outburst he fell silent for a time. By his expression, he was reluctant to be interrupted, and instead of making any comment, Carbis refilled his pipe and sat smoking. There was a knock at the door, and the policeman on duty entered.

"Mr. Danton asks if he could have a word with you, sir," he said.

"Danton?" McCleod looked at the man in surprise. "Show him in at once—"

"He's here, sir."

McCleod frowned a little as the constable turned to motion Danton inside; then his face assumed a normally amiable expression—normal to him, at least, when he was feeling particularly sinister towards the person for whose benefit he assumed it.

"Well, Mr. Danton?" he said. "Won't you sit down?"

Danton shook his head, but strode over to the desk.

"There's just one thing I thought I ought to tell you," he said. "In the excitement of—what happened—I forgot all about it. It's about Couche."

"The attendant? Yes?"

"There may be nothing in it, of course... I happened to go down to the basement this afternoon. I couldn't find him anywhere, but noticed the lower door was open. He was burying something in the border outside—a fairish-sized parcel. I asked him what was in it; he seemed scared and said it was rubbish, stuff that wouldn't burn. I wasn't satisfied, and hid. He brought the parcel in again, and lit the furnace. Then he was called upstairs. I went to the fire-hole, but all I could get out was this."

He drew the strip of cloth from his pocket and laid it on the desk. It was blackened and charred, hardly recognisable, but McCleod stared at it for a moment, and seized it eagerly.

"Couche was burning this?" he demanded.

"I've said so."

"You think that that's what was in the parcel—but you don't know?"

"I couldn't know."

McCleod thought for a moment. "He brought the parcel back? But you didn't examine the fire-hole to see if it was still there?"

"I had no time. I assumed that he'd put the parcel in the fire."

"Exactly. But he said that it was unburnable—and he might just have changed his mind, remembering that the furnace was out... By the way, what were you going to see him about?"

It was Danton's turn to hesitate. "I wanted to ask him why he thought that the Professor was murdered," he said at last. "He told me something about spies and a new gas, in two letters—under pressure."

"Just why did you want to know that, sir? Mere curiosity?"

"Not exactly. It was part of my attempt to clear Mr. Seymour. I told you the results of that."

"You saw the sergeant, didn't you? You didn't give it to him then?"

"No. Really, I wasn't sure it was anything, and it quite slipped my mind."

"You know what it is?"

"It looks like part of a pair of trousers."

"But have you seen any of that pattern?"

"I don't know... I should say it was common enough."

Danton was evidently growing even more sulky than he had been when he entered. McCleod sighed, and gave up the attempt.

"Very well, Mr. Danton. And thank you for coming to us. Oh! Just a moment. Could you show us the place where Couche was digging?"

"To-morrow, you mean?"

"I meant now." McCleod rose to his feet. "If you don't mind—"

On their way to the lower door, McCleod stopped to glance into the fire-hole. He motioned Danton inside.

"See anything here corresponding to the parcel you spoke of?"

Danton entered and looked round obediently. Then he started a little. In the corner behind the door were two other packages, similarly wrapped, though slightly smaller, and from one at least of them protruded the edge of a battered tin.

"I don't know," he said after a pause. "I think these are smaller."

McCleod nodded. "Did he say he was in the habit of doing that with rubbish?"

"I believe he did."

McCleod nodded again, rather more glumly, and motioned to Danton to lead the way. He flashed his torch on the bed at the point where Danton stopped. The two sets of footprints were clear enough.

"Here?" McCleod asked. "No, wait there, please."

He himself crossed the soil, taking care to avoid the footprints. He flashed his torch downwards, and was rewarded with a glimpse of something white. It was the edge of a newspaper-covered package. In a moment he had uncovered it. He held the beam of the torch so as to reveal it clearly, and looked at Danton.

"This it?" he asked.

Danton only stared for half a minute. He felt completely bewildered.

"It might be," he admitted after a long pause.

Stooping down, McCleod felt for his knife and cut the string, throwing back the paper. The contents were obvious rubbish, though not all in accordance with Couche's description of them as unburnable. He eyed the mess gloomily for a few seconds; then retraced his steps to the path.

"Carbis!" he said.

The superintendent had followed, and was standing by the door, an interested spectator.

"Would you mind getting this stuff inside, and have a man look round here?... Well, Mr. Danton. What can we say about this? Looks as though he only told you the truth!"

"I'm sure..." Danton began and stopped. "Oh, well. It's not my business. I suppose you can ask him. Anything more I can do?"

"No, thank you, sir. Except that, if you're going, I'd like you to mention it to the man on duty at the lodge. Then he'll know who's in the building."

He had steered Danton inside, and now he re-locked the door. Danton watched him.

"And so that you can have me followed, Inspector?" he said a little bitterly. "Don't worry. I'm not going to bolt. By the way, there's no objection to my going to inquire how Miss Roseland is?"

"Not if you think it advisable," McCleod said a little dryly. "Good night, Mr. Danton. Thank you."

He waited until Danton was out of earshot, and then turned to Carbis with a curious expression.

"Wonder what he meant by that—or what someone did? Either it happened, or he invented it.... And I don't think he did—"

"That cloth—?"

"Is almost certainly the one the fibres came from. And it belongs to Couche?"

"Or someone he's shielding."

"That's possible, too. Or it was planted on him. You see, there seems to have been a good deal of that kind of thing in this business... Well, I wonder how Ambrose is getting on? We'd better see?"

"Don't expect he's found anything. That road won't show any tracks. By the way, those footprints the woman left in the ditch seem to uphold the theory that she had an appointment there."

"Sort of sideways, by the tree—as if she was looking up the drive? Yes... Funny, isn't it, how conventionally people's minds work in the matter of appointments. You know: 'Meet me under the clock at Victoria' or 'at the hollow elm at midnight'."

"One's got to meet somewhere identifiable."

"Yes. Besides, perhaps the tree had sentimental associations— By George!"

"What?"

"Don't you see? It was night. If she was a complete stranger to the place, how did she come to find that tree, without any trouble? Why should whoever arranged to meet her say the tree, and not the white gate—where the footpath is? Isn't it obvious?"

"No," Carbis said bluntly. "Because she asked where the Institute was."

"That's true... Oh, hell. Let's go and see Ambrose... All the same, there must be something in it... Might be worth while having a few local inquiries made. Better still, get the papers to publish her photo."

"From the corpse? They're not much good."

"Perhaps we'll find one... Well?"

The plain-clothes man at the door had stepped forward with the obvious intention of speaking. McCleod remembered that he had been the man on duty in the laboratory that morning.

"Excuse me, sir," he said. "But there was a button found on the floor, wasn't there? A green one?"

McCleod nodded.

"Well, sir, I'm not sure, but when one of the young gentlemen passed me a little while ago as I was standing in the hall, I thought the buttons of his coat were like that."

McCleod's eyebrows rose.

"One of the young gentlemen?" he said. "Who?"

"I think—isn't it Mr. Wiedermann, sir?"

McCleod wrinkled his brows considering. It was only about half an hour since he had interviewed Wiedermann and taken a statement from him. So far as he remembered, Wiedermann had been wearing grey flannels and a coat of brown upon which the sewing of green leather buttons would have been a sartorial enormity of terrific proportions. He shook his head.

"You must be making a mistake," he said. "Surely Mr. Wiedermann was wearing a brown coat?"

"Not when I saw him, sir. About six o'clock. He came downstairs for a moment to go to the cloak-room— He was wearing an old green coat, sir."

"He's gone now?... Ah! Give me those keys."

Almost snatching the bunch from the man's hand, he turned towards the stairs.

"But what's the idea?" Carbis asked. "He wouldn't change his coat here?"

"Haven't you heard of people having coats for working? Lots of office workers do, even, in places where they're not on show... If you were messing about with a lot of stinking chemicals and acids and things... Let's see... This is the room, isn't it?"

He opened the door and switched on the light. They entered together, and McCleod closed the door behind them. The very act of doing so was all the search which was needed. The green coat hung in full view behind the door, and McCleod pounced upon it. One of the small buttons from the left sleeve was missing.

"Good Lord!" Carbis exclaimed. "Then Wiedermann—"

McCleod, whistling a little tune, took the coat off its nail and carried it over to the light. Producing the magnifying-glass from his pocket, he examined carefully the threads which still showed where the button had been. At last he nodded, and handed the glass to Carbis.

"What do you think?" he asked.

But Carbis peered in vain. Whatever had impressed McCleod seemed to have escaped him.

"Well?" he asked.

"Don't you think it's been cut?"

The superintendent looked again, but only shook his head dubiously.

"It might have been," he said. "But you know a lot of those buttons have metal backs. Mightn't that have done it?"

"Perhaps it might." McCleod eyed the coat again, hesitated, and finally replaced it on its hook. "It seems to have been quite safe there up to date," he said, "and there's no use arousing suspicions... And the question is, what do we make of that?"

"You don't think Wiedermann cut it off so as to give us some evidence against himself?" Carbis asked with rather heavy humour.

To his surprise, McCleod seemed to be impressed by the suggestion.

"Yes, he might have done that, if he's guilty, and if he's clever enough... You see, the point about this murder which is developing is that the murderer went out of his way to provide us with evidence against certain people. There's Thursden's fingerprints, Seymour's dart; the threads from that stuff which Danton says belongs to Couche; and now this button. Suppose that was his idea, if he were clever enough, he might leave false evidence against himself—such as a button which had obviously been cut off. It's rather subtle—"

"And I should say it was too damn' risky," Carbis broke in. "Suppose the police don't know that it's been cut off. What then?"

"Yes." McCleod eyed him comically. "There's always a risk that the murderer who's too subtle will credit the police with greater intelligence and imagination than they have... It would be a bad job, then, if we missed all the clues except the button!"

"I don't believe a murderer would risk laying false clues against himself."

"Perhaps not... Then, it would follow either that the murderer left his own particular clue by accident, or else that the murderer was one of the people whom there's no clue against. And those are—?"

"Hope, of course. Oh, and Dr. Boynley. There's no one else... Oh!—Smith?"

"But there is something against him—the poison-gas letters... Haven't you forgotten Danton?"

"Good heavens, yes. Only, of course, I was counting the dart against him. He and Seymour had both opportunities for getting that."

McCleod nodded slowly, and stood there for a moment considering.

"There are two ideas which we've not seriously thought of," he said. "One is the sort of gang-murder stuff—a combination of students all bent on killing Roseland and all lending a hand. The other's the suicide made to look like murder. How about those?"

"Only that, if there's any sense in them, they wouldn't arrange to leave clues against everyone; they'd combine to prove alibis for each other... As for the other idea, did Roseland get up after killing himself and hit himself on the head, or what? And is the Ridworth woman in the conspiracy?"

"I suppose there's nothing in it," McCleod sighed. "Only it would be rather attractive, wouldn't it? Then, there's Hope, Danton and Boynley. Hope's out of it. That leaves Danton and Boynley—with the evidence overwhelmingly against Danton... And even this last business fits in. Danton wants to make sure the trousers are traced to Couche. And yet..."

He did not finish the sentence, but led the way into the corridor, locking the door behind them. They walked along it in silence, but at the stair-head McCleod stopped to look at his watch.

"I'm still not quite happy about Boynley," he said. "Wonder if that housekeeper woman would be in bed? I'd like to hear more about that quarrel, and just how bellicose seventy-eight can be in the heat of argument—"

"Better leave it until to-morrow," Carbis suggested. "Hullo! What's this? Hell! Not another—"

But McCleod was already racing down the stairs to meet the cavalcade which was just entering the lobby below them. A police sergeant led the way. Behind him followed two uniformed policemen carrying a stretcher. And on it lay the still form of Couche.

---

CHAPTER XIII
A Night Alarm

ON leaving the laboratory, Danton had had no very clearly formed idea of his reason for visiting Sylvia Roseland, and more than a suspicion that to do so at such an hour and in such circumstances was unreasonable. He only knew that he wished to see her. But he had scarcely gone half a dozen paces of the short journey to the house before he began to be doubtful. With an inexplicable twinge he remembered how she had turned away from him when he had offered his escort to the car, preferring even Wiedermann. And besides, though free to all appearances, he was perfectly aware that he was a suspect, owing his liberty chiefly to the desire of the police to make absolutely certain of him.

He told himself that they could not prove anything against him, but the fear remained. Even if they could not convict him, even if no charge was ever brought, would he ever be able to acquit himself in the eyes of the world in general. Unless a case was proved against someone else he would always be thought guilty by some people; and somehow the dread of this stigma was blended with the thought of Sylvia Roseland. Even she thought him guilty. Danton laughed suddenly, with an intense bitterness. In any case, what did it matter? She was engaged to Seymour, and his efforts had both cleared Seymour of suspicion, and had placed himself in a position from which he saw no escape.

Half-way up the garden path, he stopped for a moment in the shelter of a great box-tree, one of the survivors of those clothing the hillside before the laboratory was built. Before he went to the house he must somehow collect his thoughts. But the more he considered, the less he knew whether to go there or not. His bitterness and even his fear had passed. Instead he found himself, in a strangely protective mood, trying to decide what would be the best from the point of view of the girl herself... After all, there was no escaping the fact that she was engaged to Seymour, and he had quarrelled with the demonstrator only that morning for lack of consideration about her. But by thrusting himself upon her and perhaps causing trouble between her and her fiancé, he himself would be showing even less. Then a new thought occurred to him which he tried to persuade himself was purely altruistic. Sylvia knew, presumably, of Seymour's alibi for the murder of the woman; she did not yet know the result of his own investigations. Slowly he worked himself into a magnificent state of mind, in which he was fully persuaded that his sole motive was self-sacrificing generosity in making Sylvia happy with the knowledge that the man she loved was safe.

He had actually started for the house again, turning off the drive along a path which he knew would be a short cut, when the simple truth brought him back to earth with a jolt. The fact was—he loved Sylvia Roseland. He did not care whether she was engaged to Seymour or not; or whether he had known her for a day or a hundred years. With the recognition came a curious joy, not unmixed with resentment. He had always ordered his emotional life so nicely, and the sudden upheaval left him confused and rather at a loss. Again contrary to all reason, it was the remembrance of her as he had first seen her outside the locked door which decided him. He meant to see her that night if possible.

All at once he stopped; but this time for a very different reason. He had heard something. On the soft grass of the pergola-bordered rose walk, his own footsteps must have been noiseless; but from where the drive swung round the hill just below him he could have sworn that he had caught the crunching of gravel. He waited for a moment, but it did not recur. That in itself was odd. He would have expected whoever was there to be walking either up or down the drive; instead, it seemed as though someone had merely crossed it, and, as his knowledge of the garden told him, on the other side was nothing but a tangle of bushes.

But nothing more happened. A little puzzled, he had almost reached the end of the walk, where it rejoined the drive near the house, when a light in one of the front windows was switched on. A patch of yellow radiance was spread for a moment over the small lawn on the other side of the roadway, and at what it disclosed he stopped again. Just for a moment, on the edge of the lighted patch, a dark figure had been visible, vanishing almost instantly into the darkness.

He waited. To his own surprise, his heart seemed to be beating at a furious rate, and every muscle seemed to have tensed. There had been something unpleasantly furtive and mysterious about the shadowy figure. Standing there in the absolute silence of the garden, he wondered whether he had seen it or not. Perhaps his eyes had played him some trick. Then from behind came a noise which made him turn quickly. It was the crash of someone falling. There was a crackling of twigs, and he heard a muttered curse.

The truth dawned upon him suddenly, and he could have laughed in the mere relief from tension, though the explanation was hardly palatable.

"McCleod's sleuths!" he muttered to himself. "Two! He's not taking many chances with me... And one of them has fallen into the rose bushes!"

He had an impish temptation to go back and offer his assistance and ironical sympathy; but he put it from him. After all, McCleod, by making the watch kept upon him as unobtrusive as possible, was really showing some consideration, and he had nothing to gain by bringing it out into the open. Instead, his plain duty was to make himself as conspicuous as possible, to save the rose-scratched policeman trouble. Taking out his case, he lit a cigarette, deliberately letting the flame of his match reveal his face as much as possible, and having so far aided his shadowers, started forward again.

It was only in the very act of ringing the bell that the obvious course to take occurred to him. He would ask for Dr. Boynley, and when he had ascertained how Sylvia was, act accordingly. At least he could tell Boynley the result of his inquiries, leaving him to tell them to his niece when he thought fit. Throwing away his cigarette, he waited for the door to open.

It seemed an unduly long time before it did so. Then he heard a key turn, and the shooting back of bolts. Blinking as the light streamed out, he saw that it was Dr. Boynley himself who stood there, peering out with more than a trace of nervousness; while a trembling maid stood in the background.

"Dr. Boynley," he began and stepped forward. "I—"

"Mr. Danton!" There was relief in Boynley's voice, and a genuine cordiality. He at least did not seem to share any suspicions about Danton. "Come in, my dear fellow—come in. You must pardon this reception. The household, I must admit, is more than a little alarmed—"

The old man's manner completely ended Danton's hesitation. He had somehow expected a certain amount of restraint, as towards a suspected murderer; but the doctor evidently harboured no such feeling. He led the way into the drawing-room, ushered him into a chair by the fire, and offered cigarettes.

"I expect that you're wondering why I came—" Danton began.

"Not at all... In fact, I was rather expecting you." He hesitated. "I regret that my niece— You will scarcely be surprised if this final blow has been a little too much for her. I am sure you will agree that she should not be excited."

"Of course," Danton assented, but he felt something very like disappointment. "It was you I was going to ask for, guessing how things would be... Only, as I had good news—about Mr. Seymour—"

"Ah, about Mr. Seymour?" Dr. Boynley echoed in a curious tone. "Yes... You say good news, Mr. Danton?"

"I'm glad to say that his alibi for Friday is completely established, and that the inspector seems satisfied. No doubt it would relieve Miss Roseland's mind if she were told."

"No doubt." But Boynley spoke without enthusiasm. He helped himself to a cigarette, lit it, and looked at Danton through the smoke. "The fact is, Mr. Danton," he began slowly, "that I'm by no means sure whether the news would be as welcome as one would be inclined to think... That must sound extraordinary, but I believe it to be a fact. I have always found women more than a little difficult in their reactions even to ordinary circumstances... I'm not sure that I ought to tell you all this, but I confess I am feeling my responsibilities acutely."

"I don't want—" Danton began uncomfortably.

"Pardon me," Boynley interrupted. "I may be a foolish old bachelor, Mr. Danton, but would you really have me believe that your interest in my niece is—well, purely Platonic, if I may employ a misused word?"

Danton flushed, opening his lips to make an indignant denial; but he said nothing.

"That being so," Boynley went on calmly, "her present state of mind is bound to be a matter of interest to you. Personally I was always doubtful about her engagement to Mr. Seymour; for my own view is that his passion carried her away... Not that one need necessarily quarrel with that, if the two people are suited in other respects. But, the truth is, I do not see Sylvia living happily with Seymour in what I may describe as his ordinary working life. Before all this happened, I believe that she was beginning to be conscious of it. The very fact of his being suspected, and needing help and sympathy, bolstered up an emotion which might otherwise have died. Now that he is definitely cleared, and besides, to some extent appeared at a disadvantage—" He broke off and shrugged his shoulders.

Danton was at a loss. He had scarcely expected any conversation of this kind, least of all from Boynley.

"My niece, I should tell you," Boynley went on gently, "was most upset, thinking she had offended you to-night—"

"I don't blame her," Danton said quickly. "The fact is, Dr. Boynley, that you're talking to a suspected man who may be charged with murder at any moment. I wanted to relieve Miss Roseland's mind, but now, it seems to me, the less you have to do with me the better."

"Come now, Mr. Danton," Boynley protested gently. "You take too dark a view of things. You must remember that Mr. Seymour has only just emerged from a similar position!" He smiled. "It seems to me you should apply your talent for detective work to your own case!"

"I don't see how I can. There's no question of an alibi for me in either case."

"No... But an alibi is not an essential part of a defence... I have been thinking matters over and I should say that, as things now stand, if charged you would be acquitted."

"And afterwards?" Danton asked.

"Ah, that is a difficulty... In that case, the obvious remedy is to secure the conviction of the real murderer... That was, in fact, the conclusion I myself reached. And, in that connection, I have been wondering if there has not been a certain amount of vagueness on the part of the police—a lack, if I may say so, of any philosophical method. Perhaps a logical consideration—"

Danton smiled ruefully. "I don't see how one can apply logic with such insufficient facts as we have," he objected.

"My dear sir, the whole study of science is a matter of applying logic to insufficient facts!" Boynley said sweepingly. "Not that I criticise it entirely. Democritus, we must remember, deduced the existence of an atomic system, which science has now largely verified... However, this is beside the point. I want you to consider certain conclusions which I have reached. The first is that my brother-in-law's death was not done on the spur of the moment; that it had been planned, almost over-carefully planned, in advance. I base this partly on the time of the murder—just before Roseland went away, and consequently when he would not be missed for two days; the place—where the body could remain undiscovered; the method—which has so far apparently defied detection; and finally the elaborate attempts made to cast suspicion on other people."

Danton thought. "I agree with the first three," he said, "but I'm not sure about elaborate attempts... Unless you know more about it than I do?"

"Well, Mr. Danton, first we have the letters—pointing, apparently, to Mr. Smith; and yet with a kind of back-wash in the direction of Couche; then we have Mr. Thursden's fingerprints on the broken glass—"

"What?" Danton asked in amazement.

"He came and told me... Poor fellow, he was most upset... And then we have the superintendent—who, I think, is at times a little heavy-handed—asking me whether any of the students wore a brown coat with green buttons; and then we have the theft of Seymour's poisoned darts... That is, by itself, enough. I do not know what, for example, the police may have against me!"

"Certainly Thursden's fingerprints could scarcely be accidental," Danton said. "He hardly went near the place— I don't understand about the coat—"

"No?" Boynley smiled a little, but did not explain. "We decide, then, that the murder has been planned in advance; even some time in advance; and that it has been planned for approximately that time... I suspect that because there is a reference to an appointment in London in Couche's version of the letters, the inference intended to be drawn being that Roseland was killed so that he should not keep it... Now, certain clues point most naturally to the laboratory as the place of the murder—Mr. Thursden's fingerprints, for example; and, for that matter, the whole idea of the unknown poison. I believe, though we cannot perhaps prove it, that the murder was intended to be done at the time, place, and by the method which was used, and that these had been planned in advance."

"It's likely enough," Danton admitted.

"Then, what follows, Mr. Danton?"

Danton thought, without obvious result. He shook his head.

"Why, did you, for example, Mr. Danton, know that Professor Roseland was going to be in the laboratory that night at the time he died?"

"No," Danton said thoughtfully. "Though, of course, I shouldn't have been surprised if he'd looked in before going away."

"But you did not know," Boynley persisted. "He might have cleared up and left everything before tea; he might not have troubled at all. But I am suggesting that, for your plan to work—of course I say 'your' in a hypothetical sense—that Professor Roseland must go to the laboratory, immediately before he would have left; that the murderer knew he would go, or could induce him to do so." He paused. "This, of course, is not proved; it is itself a hypothesis."

"I don't see how anyone could know."

"And in fact you are right!" Boynley answered. "Because, as I know for a fact, Roseland was not intending to go! He told me so himself."

"But he went," Danton objected.

"I had better explain in a little more detail. At tea-time, Roseland was talking about his apomorphine work, and mentioned that he'd just have to look in to the laboratory before he went... After that followed a whole succession of those awkward little incidents which sometimes happen to delay one. He was getting very late for his train, and said, again in my hearing, that he wouldn't bother about the flask which he had left boiling. So, when he looked in to say good-bye to me, even I was under the impression that he was going straight out by the front door. He must have changed his mind yet again, even though he had barely time for his train. And that, I think, offers an interesting subject for speculation. What conceivable argument could have induced him to go there at that particular time?"

"It must have been something important, presumably, which someone told him in the interval."

"And, in that time, he talked to no one but Seymour, and... myself!" Dr. Boynley paused. "In fact, in the latter part of the time, after Seymour left, he talked only to me! Now, if the work you did to establish Seymour's alibi is taken into account, we know that Seymour did not do it. What conclusion are we driven to?"

Danton started. He stared at the old man in utter amazement.

"But—you can't mean—?" he stammered.

"No, this is not a confession, Mr. Danton... I, personally, know that I did not kill my brother-in-law; though I cannot prove it. So, from my point of view, we have reached a kind of reductio ad absurdum; the conclusion we reach is impossible." He smiled benignly. "I had just got so far when you came," he said, and looked at Danton with great satisfaction.

"And so—" Danton began uncertainly.

"And so, either our argument, or our assumptions must be at fault... And we have to ask ourselves, at what point?"

Danton tried to take his mind back over the conversation. "We must be wrong in thinking the murder deliberately planned," he said. "The murderer perhaps intended to kill Professor Roseland that evening; but he simply had to wait for his opportunity."

"And, when it came, it turned out perfectly from his point of view? Well, it is possible—" He reflected. "In other words, it was just something Roseland happened to think about which made him, when already late for his train, go into the laboratory?"

"I suppose so—" Danton began dubiously. "Unless whoever did the murder met Roseland outside the house and somehow persuaded—"

The opening of the door broke in upon his words. He glanced towards it; then jumped to his feet in confusion. Sylvia Roseland was standing there.

"Sylvia!" Boynley said protestingly. "My dear child, is this quite wise? You should rest—"

She shook her head. "I couldn't. Then I heard the door open, and I wondered—I had to know..." She turned to Danton. "The maid told me you were here, so I came... Mr. Danton, I—I'm sorry about, about—"

Belatedly Danton stepped forward, trying desperately to think of something to say. Her eyes were searching his face.

"You must forgive me," she went on pleadingly. "I didn't really think— I don't think—"

"I—well, of course," Danton began. "There's nothing for you to bother about, Miss Roseland."

"But you did notice. It was the shock of what had happened. Just for a moment I thought—I thought—"

"That I was guilty? Well, that was natural enough." In spite of all he could do, Danton could not keep the bitterness out of his voice. "In fact, Miss Roseland, it's an opinion I imagine a good many other people still hold."

"But it's not true... And I ought never to have thought so for a moment. After I had sent you out—I—I can't help feeling that if anything happened—"

Boynley stepped into the breach. "My dear child, nothing is going to happen. I have just been talking to Mr. Danton now. I can assure you that there is very little possibility that the police will venture to charge him with—"

"But they suspect him." She looked at her uncle with troubled eyes which seemed to ask for a denial. "They do, don't they? You know that they do?"

"For that matter, my dear, they suspect all of us. Why, I've no doubt that Inspector McCleod is investigating my antecedents most carefully." He smiled, speaking rather like someone who is soothing a child. "But that is nothing for us to worry about... And, Sylvia, I might say that Mr. Danton has brought you good news. His investigations have proved that Mr. Seymour travelled by the train to London and attended the conference as he said."

The disappointing effect produced by the words certainly upheld Boynley's view of the change her feelings had undergone. She stood for a moment in silence; but there was no great relief in her face.

"I—I'm very grateful, Mr. Danton," she said. "I— Of course, I never believed... It would have been too terrible. I don't think I could have borne it—"

"However, it's all right now," Boynley suggested. "You will be able to rest now, my dear—By the way, where is Mr. Seymour?"

"He went out." There was almost indifference in her voice. "I think there's a pathologist come down from London. He was going to demonstrate—to demonstrate—"

Her voice faltered. Both men stood there uncomfortably, though Danton longed to take her in his arms and comfort her. But it was Boynley who stepped forward, and, taking her arm gently, led her to a chair.

"My dear Sylvia," he protested. "You will really make yourself ill if— What's that?"

Through the open door came the sound of a dog barking furiously. It seemed to come from somewhere at the back of the house, but Danton could not place it. As they listened, there was the sound of a heavy thud of something falling. The barking stopped for a moment; then broke out more furiously. All at once it changed to a yelp of pain; then there was silence again.

"What?" Danton asked. "A dog—"

"It—it's Peter. My Alsatian... The library— He was shut up there—"

Without waiting for more, Danton pushed past Boynley and hurried out into the hall.

---

CHAPTER XIV
Mr. Smith is Caught

LOOKING down at the prostrate man on the stretcher, the inspector drew a deep breath of relief. Couche's face was flushed, and he was breathing stertorously, but at least he was still alive.

"Thank God!" McCleod exclaimed. "I thought that he was dead— What happened?"

The sergeant stifled a grin, and glanced in turn at the unconscious attendant.

"Well, sir, he's dead drunk!" he said simply.

"What?"

McCleod, with his mind set on tragic explanations of the case, felt completely taken back. But another glance showed him that the sergeant had spoken the truth. Couche, so far as he could see, was suffering from nothing more than intoxication. Then a thought struck him.

"He's seen a doctor?"

"Yes, sir."

"And what exactly did he say?"

"Well, sir, what he said exactly was: 'My God, he has been having a good time. He's blind paralytic....' Those were his words, sir."

McCleod heard Carbis chuckle behind him; but he paid no attention. He was thinking hard.

"Where did you find him?" he demanded at last.

"A little way up Cockspur Lane, sir. Constable Jones was on his beat there, and found him in the condition which you see, sir. Jones 'phoned the station, and an ambulance was sent. When we got him there, I recognised him as the man you'd been looking for, sir. So after the doctor had seen him and said it was all right, I brought him straight here to see you, sir, according to your instructions."

"'You may take a horse—'" Carbis murmured softly. "I don't believe he can see you, McCleod—unless he sees two of you!"

McCleod shrugged his shoulders impatiently. "Has he said anything?" he demanded.

"He swore twice, sir, and once he said: 'Don't mind if I do. Good feller.' That's all, sir." The literally minded sergeant verified this point by glancing at a pocket-book. "What he said when he swore, sir, was—"

"Never mind that... How did he get like this? You'd looked round the pubs before, hadn't you?"

"Yes, sir. But we looked in the bars, sir, naturally. And as a matter of fact he seems to have been drinking all evening in the lounge of—"

"Well?"

"Of your hotel, sir!"

"He didn't go there alone?"

"No, sir. There are two of those bl— two young reporter gentlemen staying there, sir. They took him, and, so far as I can make out, they and another reporter filled him up a bit, sir, if you know what I mean, in the hope that he'd tell them a bit... They're staying at your place, you see, sir, two of them. The third—"

"Who was he?"

"He just seems to have hooked himself on, sir; but from what they said he was evidently a newspaper man. In fact, sir, it was more or less his idea, they said."

"Did Couche tell them anything? "

"So far as I could tell, sir, they'd spent their money for nothing." The sergeant's satisfaction was obvious. "Fed up, they seemed, sir. Said he spouted all evening about the Professor's habits and the laboratory and the mess the students made and being overworked, but never said a thing about the murder. Whenever they tried to steer him round to it he sort of sheered off. One of them swore he thought Couche had something to do with it, just from the way he avoided it."

"All evening, you said."

"Well, sir, from the time the pubs opened at half-past five. They met him in the Golden Lion, where they'd just slipped in to—for something, sir. After that, they just took him along."

"The third man?"

"He came in when they were in the Lion, sir. Tipped them off—"

McCleod turned to the superintendent. "Carbis," he said. "Would you mind sending to Smith's hotel, asking if he's there, and, if he is, bringing him right here?"

"You think—" Carbis asked.

"I think our third unidentified friend was Mr. Smith. And I think that he had some damned good reason for making Couche drunk."

Carbis stared a moment, and nodded. As he turned away towards the lodge to telephone, McCleod motioned to the stretcher-bearers.

"Bring him along... This way."

He ushered the procession into Hope's laboratory, where the bench made a good resting-place for their burden, who still remained sublimely oblivious to the proceedings. McCleod eyed him grimly for a moment. Then his eye lit upon a length of rubber tubing attached to one of the taps in the adjoining sink. He seized it purposefully, and turning the tap, directed an ice-cold stream down the back of Couche's neck.

The treatment was drastic enough, but it was a minute at least before the attendant showed any signs of responding.

"Blooming draught," he said indistinctly at last, and moved uneasily.

McCleod relinquished the pipe and took him by the shoulder, shaking him violently.

"Couche!" he shouted. "Couche! Pull yourself together! Get up!"

"Don't know nothing about the murder," Couche rejoined. "No murder... Cigarette-ends and papers—"

"Couche! This is Inspector McCleod—police. You've got to answer me!"

"Good fellows," Couche said gravely, and then smiled. "Didn't tell them about the trousers!"

The sergeant was grinning openly, but McCleod frowned.

"Trousers?" he demanded. "Couche! What trousers?"

"Trousers... Calls himself a gentleman... What'd he want—gimme the trousers?... for the three o'clock... each way..."

The effects of the cold water were passing, and his utterance was growing more and more indistinct. McCleod glanced at the pipe again and half stretched his hand towards it; then he changed his mind.

"Sergeant!" he said.

"Yes, sir!"

"Take him to the station. Lock him up. Get a doctor if you need one, but bring him round as soon as possible. And let me know as soon as there's any sense in him!"

"Yes, sir. The charge, sir?"

McCleod made a hopeless gesture. "What d'you think?" he demanded. "Or don't you? Maybe you don't notice anything wrong with him?"

"Yes, sir." The sergeant was quite unruffled. "Drunk and incapable, sir.... Right! Lift him—"

McCleod stood watching them with a feeling of complete frustration as they lifted the stretcher down. Quite plainly Couche knew something, and what he knew might be of vital importance. The shaking of his removal seemed to bring about a momentary return to consciousness. He muttered a few unintelligible sentences. McCleod motioned to the bearers, and bent nearer.

"Thank—Mr. Hope... Come in handy—" Couche mumbled, and again lapsed into silence. McCleod stood erect, and looked at Carbis; then he jerked his thumb towards the door and nodded to the sergeant. He waited until the stretcher had disappeared; then closed the door softly.

"You heard that?"

Carbis nodded.

"If only the damned fool were sober.... But then he wouldn't have said anything. It's pretty plain, though... Someone gave him some trousers—and he mentions Mr. Hope just afterwards. And the trousers are on his mind... And Danton said he'd burnt something and brings us that bit of stuff—?"

"I don't see where it leads, anyhow," Carbis objected. "If the murderer gave him the trousers he didn't climb through the window in them himself. And, anyhow, why only trousers—"

He was startled by the effect of his own question. For as he spoke McCleod jumped round as though he had been attacked. He stood for a moment staring at the door and his hand shot out.

"Why trousers only?" he echoed. "Carbis, you've got it! That's why!"

For a moment the superintendent thought that he had gone mad. Then he saw, and his jaw dropped.

"Good Lord!" he said. "That's the coat!"

"Yes." McCleod stood looking at it. "The brown coat we were looking for—simply hanging behind the door—like Wiedermann's. Of course, it's perfectly natural for Hope to have a working coat just as much as Wiedermann. And we didn't notice it because either he had changed it or he was wearing an overall. And presumably he gave the trousers to Couche, and Couche burnt them to-day... Where is Hope?"

"Gone home, I believe... But, even so, Hope didn't do this murder. He'd got an alibi... With Seymour."

The inspector thought for a minute. "Perhaps he didn't," he said at last. "But it will be all to the good if we can clear up even a little bit of this tangle. D'you gather what that means? It practically proves our theory that there's evidence against all of them—planted evidence. For Smith, the letters, his record and the forced window... For Thursden, the prints; Wiedermann, the button; Hope, the cloth; Couche—well, the cloth and the letters in a way; Seymour, the dart; Danton, the dart again—"

"Yes, but Danton might not have thought that the dart would be brought up against him," Carbis said. "He probably didn't think that Seymour would count his darts again and remember that they'd all been there when Danton was in his room. Seems to me the mere fact that there isn't a clue against him makes it bad."

"Come to think of it, why—" He broke off, and frowned a little.

"For that matter, there's no evidence against Boynley—no clues left," Carbis suggested.

"No. Or none that we've found... Do you know, I begin to wonder about Boynley. We've only his word for it that Roseland left like that on Friday night. None of the servants saw him. Why didn't he get a taxi—"

"Oh, Boynley told me that—the taxi. Roseland was rather keen on walking. His idea was to take the short cut to the station across the fields."

"All the same, it would be worth while asking... Now, I wonder what the hell they could quarrel about?"

"Just as many things as anyone else. They were both getting on and old men are often crotchety... In fact, I'll take my oath that Boynley's a thoroughgoing crank."

"Why?"

"Oh, I don't know... Pacifism and that sort of stuff. Sometimes he goes and talks at meetings. Perfectly daft, from what I hear."

McCleod smiled. "Then he's got quite a lot of good company in his madness," he commented. "Not that I feel that way myself... Only I don't see that's any motive for murdering Roseland, leave alone the woman."

"I don't know. When a man's a bit daft on a subject, his mind doesn't work like the minds of ordinary people... He may have gone off it altogether, and, reacting against the idea of not shedding human blood, emerges as a wholesale killer!"

McCleod laughed. "Your imagination's running away with you," he said. "Because, in any case, that wouldn't explain how that woman came to be going up the hill to the laboratory at that time of night... Hang it all, bearing in mind what she looked like, the way she was dressed—what must have been the reason for her being there?"

"A piece of someone's dark past come to life... And, after all, either Roseland or Boynley might have had one. You never know..."

"And we never shall by talking here. Let's go and see if Ambrose has found anything—that is, if nothing happens first. I'm getting a bit distrustful of this case. Whenever I try to do anything there's generally something else that I've got to attend to which crops up."

"'There was an old sailor my grandfather knew,'" Carbis quoted, "'Who had so many things that he wanted to do—'"

McCleod stared. "You're not feeling the strain?" he asked sympathetically.

"No. That's Milne. I was teaching it to my niece... And it applies to your case, too. 'That whenever he thought it was time to begin, 'He couldn't, because of the state he was in!'"

"Selections from the Classics, No. 1," McCleod murmured, and opened the door.

After all, McCleod's premonition was unjustified; for they reached the scene of Sergeant Ambrose's operations without further incident. The sergeant had entered upon the business of a night search with enthusiasm. Car headlights illuminated the roadway for some distance on either side of the scene of the tragedy, and lights flashing beyond the hedges showed where, under his direction, searchers were examining every inch of the ground. The sergeant met them on the edge of the prohibited area, and he was evidently discouraged.

"There's scarcely a trace so far, sir," he said. "You see, the road surface is much too clean and hard to leave any tracks. And so far as we've been able to find up to date, no one went anywhere else.... We've found one thing, though. It's here."

He drew a small box from his pocket, and opened it to reveal an unsmoked cigarette. McCleod looked at it in the light of the torch.

"Boynley's," he announced. "He smokes a special brand... Where did you find it?"

"Just by the small gate leading into Roseland's garden, sir. On the left side of the path."

"And, unfortunately, that's about where one would have expected it... You remember, Carbis, he was holding a cigarette when he talked to us. That disposes of the poison blow-pipe theory."

"Blow-pipe, sir?" Ambrose inquired.

"One of the things you might look for is a tube through which the dart could have been blown," McCleod answered. "Like a pea-shooter... You see, it might have been shot that way—"

"You think so, sir?" Ambrose was dubious. "It was stuck pretty well in, sir—"

"It's the way they are used, after all."

"By savages used to using them, sir. As a boy, I don't mind saying that I was pretty hot with a pea-shooter—but I wouldn't be so good now... It's practice—"

"You're not suggesting a boy did it?"

"No, sir. Only that if the dart was shot that way, whoever did it would have to have learnt how, sometime or somewhere."

McCleod nodded doubtfully. Apart from the prints of the woman's feet near the tree the sergeant had found nothing else. Almost idly McCleod moved over to the tree and looked at the place again. Only the body had been moved, and even the glove which had lain beside it was still there. And it was this which focused McCleod's attention. He frowned at it.

"Why did she take off her glove?" he asked.

"There were cigarettes in her bag," Carbis suggested. "I think it's reasonable to suppose that, having got to the meeting-place, and apparently seeing no one there, she decided to have a smoke."

"Maybe. But if it was a secret meeting—?"

He left the sentence unfinished, and going to a lower part of the hedge watched the lights of Ambrose's contingent systematically moving over the short grass. It was plain that they were leaving very little to chance; their search had already extended some distance from the roadway, both up and down the hill. But so far there had been no result, and, McCleod thought, the worst of it was that there was no reason why there should be. What traces, in fact, could one reasonably expect even an inexpert murderer to leave under the circumstances? He turned with a sigh to Sergeant Ambrose.

"What's your programme here?"

"Make as certain as we can that there's nothing more to find, post a watch and try again by morning," Ambrose answered promptly. "You see, sir, although we're doing our best with the lamps, there's not really much chance of absolutely making sure there's nothing. We'll look again by daylight. That's all right, sir?"

"Quite all right. I can't see anything else you could possibly do, and goodness knows, you seem to be making a thorough job of it, Sergeant. I see your men are right along the hill there."

"We thought, as a matter of precaution, we'd just have a look right round the boundaries of the house and laboratory ground, sir. You never know—"

"Hullo! What's that?"

From along the hillside came a shout—obviously a challenge. In the darkness near the end of the wall bounding the garden, a light flashed suddenly; then started an erratic course down the hill. Another light which had been wavering over the slope a little nearer to them joined in the chase. In a moment McCleod was scrambling over the wall.

"Head him off!" he shouted. "He's turning this way! Quick!"

Ambrose was at his heels, with Carbis labouring a few yards in the rear. In the daylight the hillside appeared as smooth as a billiard-table; by night, when one came to cross it at a run, there seemed to be all kinds of inequalities. Plunging and stumbling over bumps and hollows, McCleod led the intercepting party. He had not switched on his torch, and in consequence the fugitive, whoever he might be, must have less idea where the pursuit was than they had of his whereabouts; for, from the purposeful line of the lights, it was possible to tell with some accuracy which way he was going, though he himself was invisible.

From half a dozen points on the hillside lights and the sound of footsteps showed that Ambrose's searchers had awakened to what was happening. McCleod had run twenty or thirty yards when he judged that he must be somewhere near the course of their quarry. He stopped and listened. Ambrose and Carbis came to a halt beside him. But the hillside was unduly full of noises; it was impossible to place anything accurately. Bending down, McCleod tried to obtain some kind of silhouette against the sky. The lights of the original pursuers were getting near. Suddenly, without any warning sound, a figure loomed out of the darkness, some distance to one side of where McCleod had expected. Taking a chance, he flashed his torch and shouted.

"Here! This way! Here!"

The light caught a hurrying figure for an instant; then the unknown swerved out of its path. But there were more lights ahead. McCleod switched off his torch and stopped again. If his guess was right, the running man would prefer doubling back to making an attempt to break through the line ahead. He crouched down, waiting. Carbis and Ambrose seemed to have disappeared. Quite near him he heard something move. Then, at no more than a moderate pace, he saw someone walking diagonally down the slope no more than a couple of yards away. He gathered his muscles for a spring and jumped.

The attack must have taken the other completely by surprise; for he evidently had no idea that McCleod was waiting in the darkness. But he did not even go down. McCleod found himself struggling desperately with someone at least his equal physically, and as slippery as an eel. Twice he thought that he had got a hold, and twice his opponent evaded him. Then he himself was gripped, and with despair he recognised the hold. It was a ju-jitsu trick, and he could do nothing. As he felt himself going down, a light flashed just behind him. He heard the voice of Ambrose.

"Inspector! Inspector McCleod!"

He shouted in answer, as his conqueror released his grip and he fell headlong. The fall was a heavy one, and for half a minute he lay there before he staggered to his feet. From somewhere just in front came the sound of a confused struggle, but he could see nothing. On the ground a few yards away a torch which must have been knocked from its owner's hand was still shining. McCleod, still shaken from his fall, made his way unsteadily towards it, and turned its beam towards the place which seemed to be the battleground.

At the first glimpse, the mass of arms and legs looked like nothing so much as a combination of several all-in wrestling bouts. McCleod identified the lower half of the superintendent; his head and body were buried in the mass. On the outside, as if hovering round a rugby scrum, Sergeant Ambrose was moving to and fro, evidently alert to catch anyone who should attempt to fly. Apparently it was his torch that McCleod had found; for he was without one.

With the showing of the light, the mêlée began to disentangle itself. Other police were coming, forming a ring of illumination round the tangled group. Dishevelled, breathless and triumphant, Carbis emerged, still gripping the man whom he had been the first to bring down. He dragged him towards where McCleod stood, with a force scarcely justified in view of the fact that the man was no longer struggling.

"Here!" Carbis grunted breathlessly. "Let's have a look at you!"

He pulled his victim forward into the beam of McCleod's torch, and the light fell full upon his face. McCleod uttered a joyful exclamation. It was Mr. Smith.

---

CHAPTER XV
An Explanation

IN appearance Smith had changed greatly for the worse since he had smiled good-bye to them at the hotel that afternoon. Perhaps under the vigorous treatment of the superintendent, his collar had completely slipped its moorings; his tie was round one ear. Somehow in the struggle both coat and waistcoat had almost been stripped from his back; and a portion of one trouser leg had been torn right out, showing two long red scars against the white skin. To add to the effect of the mud on his face he had the makings of a magnificent black eye. But he eyed McCleod with dignity.

"'Væ victis!' Inspector, and all that," he murmured with a suggestion of reproach. "But is it necessary to chortle? Is it official? Would you not be more properly employed in asking me if I have any statement to make, and warning me that anything I say may be taken down and used as evidence?"

McCleod was a little taken aback. Apart from the disfigurement of the struggle, Smith seemed somehow to have altered; his whole manner was different, and he certainly showed no sign of being a man on the verge of facing a capital charge. But McCleod was wary. He had caught Smith before, and damning as the evidence against him seemed at this moment, there might still be a catch in it.

"I greatly regret, Mr. Smith, if we have been compelled to use any force," he said with more than a trace of sarcasm. "No doubt there is some mistake, and you can explain everything?"

"I can," Smith answered obligingly, "in at least six different ways, Inspector. I might, for example, ask by what right your hired assassins interfere with a man enjoying a quiet stroll, attack him, man-handle him—and even bite a piece out of his trousers! And what would your answer be to that?"

"I should ask you why you ran away," McCleod said simply.

"Exercise," Smith rejoined. "Or, I might well reply that I was nervous when a man with a nasty rough voice shouted to me out of the darkness—in a place where, despite the police, murders are so frequent."

"Look here, Smith, what's the good of this?" McCleod was getting impatient. He had a ghastly feeling that after all the cards must be in Smith's hands. "You know we've got you—"

"On what charge, Inspector? As you have no doubt ascertained, I can prove an alibi for this murder."

McCleod hesitated. In fact, they had not yet received positive evidence, but he was morally certain that Smith had been concerned in the intoxication of Couche. And, if that was so, he was certainly innocent of killing the woman. Then, what had he done, except run away from a policeman he could not see?

"Much as I hate to disturb your meditations, Inspector," Smith broke in, pointing to his leg, "I should like to suggest that, unless this receives attention soon, you will be put to the trouble of carrying me either to hospital, to gaol, or to the mortuary."

There was a weakening in his voice which made McCleod flash his torch down on the injured limb; then bend down to look closely. The injury was worse than it had appeared. Two ragged furrows ran down each side of the leg, and the boot below was covered with blood.

"Good Lord!" The exclamation was forced from McCleod. "How on earth—"

"Do police bites give one hydrophobia?" Smith asked a little faintly. "You might ask your men for the piece of trouser, Inspector. Perhaps I could patch—"

But in the middle of the sentence his voice trailed away. The next moment he collapsed unconscious into the superintendent's arms. McCleod jumped forward.

"Here, bandage that leg!" he ordered. "Lay him down, Carbis... No, he's not foxing. It's loss of blood. How the hell—"

The answer to the question came next moment from up the hill. A constable touched McCleod's arm and he looked up. Near the house lights were flashing and he caught the sound of shouting.

"He's been at the house!" Carbis exclaimed. "That's where he hurt his leg—"

McCleod eyed the wounded man. "We'd better carry him there," he decided. "I wonder what the devil— We'd better go and see... Bring him along as soon as he's bandaged."

McCleod was silent as he hurried up the hill, and though they could not see his face, Carbis and Ambrose, who accompanied him, did not venture any questions. They had nearly reached the house when a figure emerging suddenly into the beam of the sergeant's torch made McCleod challenge sharply.

"Who's that?"

"Is that you, Inspector? Thank Heaven!" It was Boynley's voice, and a moment later he appeared in the full glare. "We—we have had a burglary, Inspector. In Roseland's library—"

"A burglary? What happened?"

"We heard the dog barking, and then suddenly become silent. When we got there, the dog lay unconscious, with a piece of bloodstained cloth in his mouth; the window was open... Mr. Danton started in pursuit."

"The library?" McCleod echoed. "Ah... Here's Mr. Danton now."

"What's happening?" Danton burst out. "We've been—"

"We've arrest—stopped a man we found running away from the house," McCleod explained. "He's hurt. We're bringing him up... It's Mr. Smith."

"Smith!" Danton exclaimed. "But what—"

"Let's get inside!" McCleod snapped. "We don't know yet! Perhaps when we've seen the library—"

But the library, when they entered it, brought little help. Except for the open window and the great Alsatian which sprawled upon the carpet beneath it, the only sign of any disturbance was an overturned chair and a few spots of blood. McCleod pointed to the safe.

"That's what he came for, of course. Remember this afternoon, Carbis?"

"Lord! He was pumping us all the time!"

"And then pumped Couche to learn a few details about internal arrangements... Couche does odd jobs here during vacation times... And we practically told him all he wanted!"

"Of course, we shall have to look round," Carbis said. "There may be prints—"

"There won't be," McCleod answered with conviction. "The dog's got the only evidence—in his mouth! Look at that cloth... It's enough, too."

The arrival of the ambulance party carrying Smith interrupted further investigations. Smith had regained consciousness, and smiled blandly at McCleod.

"Bring him in here," McCleod ordered. "Better send for a doctor—"

"And an undertaker," Smith murmured. "Inspector, far more than any medical aid, I need medicine for the soul... In fact, if you send this mob away, I'll come clean!" He caught McCleod's suspicious glance, and added quickly: "Oh, Ambrose and the superintendent can stay... If I could have a drink—"

McCleod poured him one while Ambrose ushered out the onlookers, and, at a word from McCleod, removed the unfortunate dog. Smith put down the glass and drew a deep breath.

"That's better," he said. "Now, I'll talk... Mine's a sad case of valour in old age getting the better of a lifetime of discretion—"

"Look here, Smith," McCleod warned him. "This isn't a matter for joking. At least you're faced with a serious charge, and I needn't warn you that—"

"You needn't. Anything I say may be used in evidence. Quite. But I hope it won't be."

McCleod raised his eyebrows.

"Here's a full confession." Smith had dropped his rather pedantic way of speaking; his face seemed to have grown younger. "And, I might say, Inspector, the whole thing's your fault. You would have it that there was a secret poison gas here. Well, there isn't. Not in that safe, anyhow!"

"What? You've opened it?"

McCleod looked at the undamaged surface of the door. There was not a trace.

"I have... And although the whole district seems swarming with cops, I should have got away with it, but for two things. First, the perfidious Couche in his cups failed to let me know Roseland possessed an Alsatian, and, moreover, one of that peculiarly vicious type which lets you get in and lies low until you try to go... I thought I'd pumped him thoroughly, too. And, secondly, one of your searchers had got a bit fed up with searching and was sitting down in a ditch to rest. I fell on top of him."

"You admit the burglary?

"I do... But, as I say, I blame you for rubbing in that idea of poison gas until I believed in it."

"Regarding the Alsatian," McCleod explained, more to gain time than anything. "It wasn't Roseland's but his daughter's. I doubt if Couche knew of it... You made him drunk?"

"Ably assisted by two gentlemen of the Press... And, Inspector, that, I might say, is all I have had to do with the sinister events of the past few days. I didn't kill Roseland; I simply came on a friendly visit; and I didn't, as you know, kill the woman, whoever she was... And I'm hoping you'll oblige an old enemy and drop the burglary charge!"

McCleod did not respond to his amiable smile. He was obviously bewildered.

"I suppose you've some reason?" he asked. "You've some explanation?"

"I have... 'Zeal, all zeal, Mr. Easy!' I'm a case of it... The trouble is, I don't know how to explain... I'm not sure that I ought to explain. That's the devil of it... However, I'm retired—"

"Retired?"

"Look here, McCleod, you and I had a good bit to do with each other in the war, didn't we? And I always got away. It must have seemed miraculous—as though I was a mind-reader, or something. Well, I'm not. Your bosses were tipping me off!"

"You mean—?" A light was beginning to dawn in McCleod's mind.

"I mean to say that, instead of spying, I was engaged on counter-espionage work—and my job was to lead the others down the garden path into your hands... Well, doesn't it fit in?"

McCleod said something beneath his breath. He stood there for a moment staring down at Smith. Then he grinned.

"And I thought—I thought— D'you know, you've been a bogey to me for years?"

"You believe it, then?"

"Why—I do." McCleod's grin vanished. "But, you see, the trouble is that I ought not to take that into—"

"Now, listen!" Smith urged. "I hear that there's the secret of a poison gas here, and that the place is littered with spies. Well, apparently they didn't get it that time; but they might if nothing's done. My idea was simply to find out if there was anything there, and, if so, get on to someone who could do something. It's only a technical housebreaking, really—"

"Would they vouch for you?"

"I don't know... They might excommunicate me for letting it out at all... Look here, why not ring up the Yard to-morrow, and get in touch with the Assistant Commissioner? He was— Well, you might try him!"

"And what the hell do I tell them here?"

"Why, that I saw a man getting out, went in to grab him, and got bitten by the dog... That's easy!"

McCleod took a pace or two up and down the room, and turned sharply.

"So, as a matter of fact, you don't know a thing about this business?"

"Not a thing... My visit to Roseland was purely social. But I've guessed some since—with the help of Couche. And I'd bet any money you'd get him—if you show the form you did with me."

"I wish I knew how," McCleod groaned.

"Well, I've been trying to work it out from what I know, and it's the business of the letters which strikes me. You see, I wrote to Roseland a week or two ago saying I might be coming; and then later saying that I was... Supposing he'd dropped a word when he read my first letter at breakfast, sort of saying: "I've an old friend coming down—a spy like me, ha! ha!' or something like that... If anyone was thinking of killing him, mightn't that be the beginning of the whole poison-gas business?... And then the murderer plants the letters, for Couche to read—and Couche only. The murderer knows that Couche, if anything happens, will broadcast the information at once. How about that?"

"I'd reached a stage approaching that—if you weren't guilty... And then?"

"Well, the number of people he'd make a remark like that to must be strictly limited. His brother-in-law, Seymour, perhaps—"

"Seymour's out of it."

"Would he tell the students?"

"I doubt it. They weren't on good terms. Except Hope."

"Then that leaves Boynley!"

"And he's absurd!"

"Well, then, Hope?"

"And he's out of it, too! Besides, there's not a scrap of real evidence against Boynley—"

Carbis broke a long silence. "And we agreed that there probably wouldn't be against the murderer," he said. "There's something planted against everyone else... Boynley could do it—except for that head wound, and I'm not sure that couldn't be managed... He'd the opportunities, both for murdering and planting clues—"

"But this woman? Damn it, Boynley's nearly eighty!"

"You don't know how old the connection might be— How old would you say she was?"

"I suppose thirty-five. Hard to tell."

"Knocking off, say, fifteen years would leave Boynley a gay young spark of sixty-three... It's possible!"

McCleod did not share Smith's optimism. "I'll try him," he said. "But—"

"Well, here's another possibility. There was a flask boiling in Roseland's room, wasn't there? Suppose something was dropped in which would make a gas—and enable the murderer to kill at a distance?"

"The trouble is, the doctors aren't decided yet. They've found no poison... As a matter of fact, Danton's our likeliest."

"That young man? Wouldn't hurt a fly... And would Roseland tell him—about my coming?"

"Very unlikely... But everything— Hullo! Come in!"

Percher, the plain-clothes man, entered and closed the door behind him. He looked at Carbis.

"Mr. Seymour has come back, sir. With the surgeon, I think they've something to tell you—"

Carbis looked at McCleod who hesitated a moment, glancing at Smith. He nodded.

"Right. Bring them in here."

Smith grinned, looking after the man as he went out; then at McCleod.

"You can remove me, if you like. Sorry I can't walk... As my bona fides isn't established—"

"That's not worrying me," McCleod said untruthfully. He was thinking in reality that a moral certainty is not enough for police work. "I don't expect they've much— Ah, good evening, Doctor. Good evening, Mr. Seymour... I hear you've got news?"

"Not exactly." The doctor came forward to the fire and stood by the mantelpiece. "Hullo, you've a patient here? Better let me look—and cauterise it!"

"No," Smith said firmly. "No cauterising... Life's painful enough without that—and that dog's not mad—only dutiful.

"Sorry, Inspector."

"Well, you can tell me something?"

"Tentatively. The analysis isn't complete, naturally. You supply the corpses too quickly... So far as we know at present, you can nearly bank on this. Roseland wasn't poisoned. He died of heart failure—perhaps following the blow. And the woman was poisoned, by one of those darts."

McCleod made a grimace. "Thank you for nothing!" he said. "Why, man, there was one sticking into her when we found her!"

"Yes. But now we've proved that it was what she died of. Mr. Seymour's test for the arrow poison seems conclusive... I don't mind saying that without that, if the dart had been withdrawn, we shouldn't have known what to make of it."

McCleod looked at Seymour. His eyes were screwed up, and he was regarding the man on the couch, perhaps trying to reconcile Smith's new manner with the man as he had known him.

"Yes, but Roseland?" he insisted. "I don't see how that blow on the head could have been inflicted by normal means—while he was conscious, anyhow. Isn't there a possibility of some unknown poison—"

"Unknown poison!" The doctor snorted. "There isn't one. I mean, there isn't a poison which doesn't leave traces."

"What about Danton's new alkaloid?"

"If he's made it. We've not analysed that stuff from the waste box yet—at least, we've not found out what it is—"

"Because it is new... Then that's all you can say?"

"Except to confirm the time of death. Roseland died just after dinner, for one thing—"

"You can spare the details... So that's all you can tell us?"

"At present... If we should find a poison—" He shrugged his shoulders. "Well, you shall have it. But don't build on that. My bet's against it. Good night."

"Good night, Doctor— Oh, Mr. Seymour!"

Seymour, who had been following the doctor out of the room, turned on the threshold, looking a little startled. He came slowly across the room towards them.

"If you'd just sit down a moment, Mr. Seymour," McCleod invited, "there's one matter which I'd like to ask you about... Of course, it may not be material to our investigation; but on the other hand, it may... I wonder if you can remember an occasion about a fortnight ago when Dr. Boynley and Professor Roseland had—well, a rather heated argument?"

Seymour looked from one to the other, and his eyes turned uneasily to Smith. McCleod caught the glance.

"You need have no hesitation in speaking before Mr. Smith," he said. "He is assisting us."

"Mr. Smith is assisting you? Oh," Seymour said a little blankly. "An argument, Inspector?"

McCleod nodded. Seymour affected to consider deeply, but it was plain that it was assumed. On the whole, McCleod did not blame him. It was unpleasant to be asked to give what might be incriminating evidence against the uncle of his fiancé.

"That was what I asked, Mr. Seymour," McCleod said briskly. "A very heated argument."

"Roseland and the doctor used frequently to argue," Seymour evaded. "So often that I don't remember—"

"I don't think you've forgotten this one," Mr. Smith interposed firmly, and McCleod was grateful. It was plain that on this subject Smith knew a great deal more than he did, and whether he was what he pretended or not, his questioning of the servants and Couche might as well be turned to account. "Let me recall some of the circumstances. You were discussing war under modern conditions—yourself, Dr. Boynley and the Professor—after dinner. Professor Roseland was arguing the necessity for complete national independence; you were in favour of some collective system, and Dr. Boynley adopted the complete humanitarian pacifist standpoint. Mrs. Robertson was there part of the time... Does that assist your memory?"

"It was a matter we frequently discussed—one of which Dr. Boynley—both of them—held particularly strong views," Seymour said; then, as if deciding that further postponement would only make matters worse, he took the plunge. "Yes, I believe I remember it. Well?"

"In the course of a very heated discussion, the proper attitude to be adopted by scientists came up. Professor Roseland held that every scientist should do his best for his own country. What was Boynley's attitude?"

"He—well, he was always opposed to any scientific developments of armaments," Seymour said slowly, weighing his words. "I believe that was his attitude on this occasion."

"With particular reference to poison gas, I believe?"

Seymour made an unconscious gesture suggestive of surrender.

"Yes," he said.

"Dr. Boynley was particularly excited in this connection. Speaking of a scientist who had invented a new poison gas, did he use some words like 'The man who killed him should receive the thanks of his fellows as much as though he were destroying vermin'?"

"Something of the kind." Seymour shifted uncomfortably.

"Roseland was amused and suggested himself as a case in point. Dr. Boynley, I believe, said something to the effect that there were no exceptions... That is correct?"

"Yes."

"And then?"

"Mrs. Robertson had already left," Seymour said slowly. "I myself left almost immediately afterwards. The argument was assuming a tone which I did not like, and, frankly, I was afraid of the effect it might have—"

"On what?"

"On Dr. Boynley. He was violently excited—quite unlike himself."

Smith nodded and looked towards McCleod. He had evidently exhausted the sum of his knowledge on the subject.

"Can you remember anything more, Mr. Seymour?" McCleod asked.

"No. Oh, no!" Seymour said eagerly. "That was all, I am sure."

"There was no further reference to it?"

"Professor Roseland made a joking allusion to it next morning," Seymour said. "Something like 'Boynley would put me in a lethal chamber.' Boynley said nothing. I suppose it was just forgotten."

"They were on good terms usually?"

"Oh, yes," Seymour assented eagerly, and hesitated. "Naturally, they had occasional differences—"

"Differences?"

"Arguments, I should have said. Principally on subjects allied to that one... You see, Inspector, that and the benefits of a classical education are almost the only subjects on which Dr. Boynley seems to feel deeply. But there was nothing, really. Ordinarily they were the best of friends."

"I've no doubt," McCleod assented politely. Then he paused for a moment. "There was one thing I was wondering about, Mr. Seymour," he said a little hesitantly. "And, as it's partly scientific, I wondered if you could help me? It's this. Couldn't there have been a kind of delayed action about Roseland's murder?"

"I don't understand—"

"Well, one of my difficulties is that a laboratory is rather outside my stamping-ground. But I've just wondered, and it would be interesting to hear your views as a scientist. Need anyone have been there when Roseland was murdered? There was that flask boiling. Mightn't something have been put in there to give off a gas? Or that glass jar— If Roseland took out the cork not knowing there was anything inside—"

"It's possible," Seymour admitted. "But it seems to me it would be difficult. I don't see how it could be done very long before. In the afternoon, perhaps—"

"And you'd be ruled out then, too," McCleod smiled.

"Thank you, Mr. Seymour. I think that's all."

But Seymour seemed reluctant to accept his dismissal.

"I can assure you, Inspector," he said, "there was no harm in it—"

"Of course not," McCleod assured him suavely. "Thank you. Good night."

There was a brief silence after Seymour had gone out. McCleod was going over the various circumstances in his mind, and feeling more and more puzzled by them. Carbis broke out suddenly.

"But it's absurd!" He turned to Smith. "You've just been telling us that the letters were fakes; and then you bring up this which demands they shouldn't be!"

"Not necessarily," Smith persisted. "The letters might have been fakes. But they might have been faked for Boynley to see. By someone who wanted to use him!"

"Fakes!" Carbis shouted, half jumping to his feet. "And, by George, they were fakes! McCleod, you remember my saying I thought the name was familiar?"

"Clibbens? Yes."

"Well, good Lord! It ought to be. It's the name of our local Inspector of Taxes!"

McCleod stared at him. On the couch Smith was chuckling.

"Yes," he said. "If one got a letter from the taxation authorities and rubbed or bleached off the type—and a scientist could do that easily enough—you could make a letter which would look official enough—to a man like Couche. But Boynley?" He shook his head. "Doesn't Boynley pay income tax?"

"Presumably... Besides, even if the letters weren't fakes," Carbis pursued his objections inexorably, "what earthly reason could there be for Boynley to kill the woman?"

McCleod sighed. Then another thought occurred to him.

"There's one clue we've done nothing about yet. You remember—that slip of paper with the nonsense written on it."

"Nonsense?" Smith asked with interest.

"Like this." McCleod scribbled the letters down on a piece of paper and handed them over. "I'm trying to have them deciphered—"

"'Itastuas tariterqui,'" Smith read out aloud. "Now, that seems familiar..." He frowned at it for a moment; then his face cleared. He laughed. "McCleod, the Scotland Yard experts haven't a hope of solving it!"

"Why?"

"Because it's not a cipher... Look here, I don't know if you know all that about the criticism of classical texts? No? Well, the point is that they were copied out time and time again, sometimes by people who didn't understand them or couldn't read the writing of the man before them... So, every now and again, you get a bit in a text which, as it stands, is sheer nonsense; and the scholars all start emending it... This is one—and a famous one. It's from a Latin writer called Lucretius—"

"Lucretius!" Carbis exclaimed. "And Boynley's preparing a book on Lucretius.... If we'd a specimen of his writing..."

He crossed over to the table purposefully, glanced over the papers which covered it, and seized the top sheet of a pile of manuscript.

"Here!" he said. "This is a bit of his book... Now, McCleod. What's the verdict? The same?"

"The same—undoubtedly," McCleod agreed without enthusiasm.

"Then, surely—"

"What?" McCleod asked. "Don't you see, it merely puts him among the great majority who have got clues planted against them... That's all." He paused. "If you ask me, down here we're getting fogged in exactly the way the murderer meant us to be fogged. Roseland's murder was deliberate and ingenious. But the woman's must have been done more on the spur of the moment. I believe that's the one we should concentrate upon."

"That's just where I don't agree with you," Smith rejoined. "It's just when criminals are excessively ingenious that you get them. I'd have a bet—if I could move about, and if I were in a position to do so—"

McCleod eyed him for a moment, and his expression was difficult to read.

"You'd better take care of yourself instead," he said. "And Carbis can look after you... I'm going up to London to-morrow."

"There's just one thing," Carbis said rather belatedly. "I didn't quite get what you were aiming at in your questions to Seymour. After all, someone would have to have been there to make that wound on the head, even if no one was there at the time of the murder."

"Quite true. I just wanted to see how he'd react to it... Oh, I know that he's ruled out really, but one never knows—"

"He didn't seem to react at all."

"He didn't. And anyway, as I said, he'd be out of it even so. Because, you remember, he said that he was out with a friend all afternoon—and even gave us the name. We could check that up. Oh, well. Let's hope I've good hunting in London."

---

CHAPTER XVI
The Trail in London

TO McCleod, being in London was like returning to his native heath. It was quite true that, like many other recruits to the Criminal Investigation Department, he had actually been country bred; but from the time he had started as a uniformed constable patrolling the streets London had been his real home. Though, as one of the senior detectives at the Yard, he had frequently made excursions into the provinces, he had always felt them to be excursions, and the sight of the first long lines of suburbs made him feel that he was coming home.

He had gone to bed late the night before, and he had been up early that morning. When he arrived at the office, he was feeling far from his brightest; but this seemed to matter little. Not one of the inquiries which he had put through regarding fingerprints or identities had produced the least result; but he had expected nothing else. From his reading of the case, he had to deal, not with habitual offenders known to the police, but with someone taking to crime for the first time.

In a brief interview with the Chief Constable, he explained the results of their investigations up to date. His superior listened with attention.

"You've not wasted your time," he said. "Plenty to go on with... But this second murder is a bad business."

"I don't see what we could have done to avoid it, sir," McCleod said defensively.

"Nor I... But the newspapers take hold of it rather if a murder is committed when we're actually on the spot... I agree with you that there's not the slightest doubt there's a connection between them. And, in spite of all frills, I'm inclined to think that it's the obvious one."

"Someone got into a mess with a woman and was blackmailed, sir? Yes, that's my reading of it."

"I think you're right, too, in concentrating for the time being on the woman. After all, it must be possible to show she knew one of them... The Divisional Superintendent's been there, by the way. If you get in touch with him, he'll take you along.... What are your objections to Danton as a murderer? You seem to be missing him out just now."

"I don't know, sir. I nearly arrested him once. But now, I don't mind saying, I think it must have been someone in closer association with Roseland. After all, Danton didn't even like him. I gather he was barely civil."

"And, in fact, Roseland seems to have been a swine in many ways. Thursden's another man you seem to have cut out."

"He doesn't fit in a number of ways, sir—or I think not. You see, sir, although the murderer may not succeed in his object of hiding who did it, his scheme certainly gives the police more work. One's got to take the likeliest first."

"But your only likely one just now seems to be Boynley. I'm bound to say I think he's too old... However, you're on the spot... You'd better see about the woman."

"Yes, sir."

"Good luck, then."

Outside on the Embankment, he wasted a few minutes revelling in the sheer joy of spring in London. He had been an exile for only a day, but his time had been so fully occupied that it seemed a century. The tide was high, and a light wind was blowing up the river. He leaned on the parapet for some minutes watching it before he could bring his mind to the necessity of going to Wandsworth. Hesitating between the Morden tube, a bus, and a taxi, he finally chose the second. As he took a top seat in front he was not thinking about the case at all.

The Divisional Superintendent who received him was a large, cheerful man with a rather ruthless enthusiasm for his job. He had already explored the possibilities presented by the woman's lodgings, and seemed if anything over-optimistic.

"Of course, she was the kind of woman who gets murdered," he told McCleod cheerfully. "And she seems to have made a good job of it. Quite a star case, isn't it?"

"Quite," McCleod agreed. The other's jealousy grated on him a little. "How do we get there?"

"Oh, I've a car. We'll go right along."

Mary Alice Ridworth's lodgings proved to be in one of the dingiest parts of a suburb which, in McCleod's estimation, only the common redeemed from utter drabness. The landlady who received them had the alert eye and wary manner induced by lodgers of doubtful reputation and financial standing. The superintendent introduced him.

"This is Inspector McCleod, who is in charge of the case. Now, I'd like you to tell him what you told me, and anything else you've remembered which may be relevant—which may have anything to do with the case."

The landlady studied McCleod, and her grimy hands smoothed her apron.

"Really, sir, I don't know," she said, "these have always been respectable lodgings. What's going to happen to me now I don't know. Who'll take rooms when the last tenant went and got herself murdered—"

"Plenty," the superintendent said unsympathetically. "Murder isn't catching... When did Miss Ridworth come here?"

"About six months ago, sir. And sometimes she'd be in work, and sometimes not, but until a month ago she was always regular with her rent, sir. And then I don't mind saying, I had to press her a bit. After all, sir, we've all got to live..."

"Yes," McCleod agreed. "You don't know where she came from? What she did before?"

"Well, sir, she had told me that she was in service till she had her trouble. In the country, sir. In fact, sir, that was what she said to me just before she went away. 'That's where I worked,' she said, 'and there's a man there who owes me something. I'm going to collect,' she said."

"And you?"

"I lent her the two bob to make up the fare—throwing a sprat to catch a mackerel, as one might say—her trunks being here.... Not that there's all that in them—hardly enough to cover. But she was so sure. And she set off and went—"

"Went where?" McCleod asked patiently. He was perfectly well used to listening to people who could tell nothing in the proper order. "I suppose she told you?"

"That Juliana place—where they make the chemicals."

"The Juliot Research Institute?"

"That's it, sir. Those were the words she used. When she saw the paper, she said: 'Well, he thinks he's rid of me, but he's not,' she said. 'I've a claim on him, and I'm starving here,' she says. 'I'm going off to collect.' And that's what she did, sir, poor thing. But she's not the first—"

"Perhaps you'd better begin at the beginning," the superintendent suggested. "Tell it as you told me."

"Well, I'd been pressing her a bit for her rent, and I won't deny it. What was I to do? And she putting me off with promises. But she was a pleasant enough girl, though not the tidy sort, and I thought she'd raise it... It was about three weeks ago, sir, that she came in with a paper, and was excited. 'I'll write to him,' she said, 'now that I know where he is. He'll help me out.' And she did."

"Write to whom? You didn't see the letter?"

"No, sir. And he didn't send, it seems—or she hung on to the money... And then another day I lent her The Times—I'd found it in the bus, sir, and it's not my sort of reading. And she came down to me and she says: 'Well, he thinks he's rid of me, but he isn't,' she says—"

"Yes," McCleod interjected. "She didn't mention a name?"

"No name, sir. But it was a gentleman she'd met while in service and he was at the Juliana place, sir."

"How long ago?"

"How should I know, sir? Only before she came here."

"You'd no idea what her intentions were when she set out?"

The landlady did not meet his eye. "Well, sir, I thought the young gentleman would like to help her—" she began.

"The young gentleman?" McCleod asked.

"They're mostly young, sir."

McCleod nodded, and his lips set a little more tightly. There was something about the sordidness of the tragedy which pierced a skin hardened by years of work not dissimilar.

"So you never knew who she went to see, or what the circumstances were?"

"No, sir," the landlady agreed. "But I thought it would be all right... And then she gets herself murdered, sir. And who's to pay me her rent? What's in her trunks won't do that—"

The superintendent, who had evidently endured all this before, cut her short.

"Thank you," he said briskly. "We're grateful... Now, we'll just have a word with Miss Reade—"

"Oh, her!" the landlady sniffed. "Well, you know your way. I've my work to do."

"And we'll need to look into her rooms again," the superintendent added before she had time to depart. "They're not locked?"

The landlady shook her head and went out. McCleod looked at the superintendent, who shrugged his shoulders.

"There's a pile of letters there," he said. "You might make something of them... It's up here."

McCleod followed him thoughtfully up the stairs. "She was blackmailing someone, of course," he said after an interval.

"Of course. And, putting it crudely, the landlady was, so to speak, grub-staking her... Here's the room."

It was a dingy bed-sitting-room, sparsely furnished with second-hand oddments; and the few tawdry signs of its recent tenant's personality would clearly not take long to explore. The superintendent jerked his thumb at the trunk which stood by one wall.

"Nothing in that," he said. "I've looked through. But look again if you like... The letters are here."

He opened an ornate chocolate box which stood on the dressing-table, and indicated the heap of papers it contained. At the first glance McCleod saw that they were certainly not in Boynley's handwriting. If the style was any indication, they had been written by a younger man; but he did not know the writing. He seated himself on one of the two chairs, and began to read.

For the most part they were normal enough, except that they were extremely non-committal. The writer of them had clearly been at some pains to keep the secret of his identity; and he had given very little away. Oddly enough, they reminded him of sonnets written by Elizabethan poetasters in the high-flown, conventional language of the period. To the two people concerned they might be significant; but to outsiders the great bulk was meaningless. And yet, here and there he found phrases which he felt were relevant. There were references to "the usual place", where apparently letters might be left; to "the tree" as a meeting-place, and two or three times scientific expositions which the recipient of the letters was probably less qualified than most people to understand. The signature was invariably "Herbert", and, so far as McCleod knew, none of the possible actors in the drama bore that name. It was no more than he had expected; and the whole correspondence bore the mark of a clandestine affair carefully concealed and discreetly managed. He finished the last of them and looked up at the superintendent, who was smoking a cigarette and looking out of the window.

"If you can't be honest, be careful!" the superintendent said cheerfully. "He was, wasn't he?"

"Yes, he was," McCleod agreed. "Whether he was careful enough or not, I don't know... You said there was a friend of hers somewhere?"

"Next flight. You won't get much change out of her... And she doesn't know all that, either."

The friend proved to be a cheerful-faced girl of the gamine type which thrives under any conditions. But she eyed them suspiciously, and with more than a little hostility. Even the Divisional Superintendent was more than a little nervous of her.

"Miss Reade," he began almost apologetically. "This is Inspector McCleod. He is investigating the death of Miss Ridworth—"

"Investigating!" There was a scornful smile on the girl's lips. "Well, why don't you hang the rotter that did it, then?"

"It's what we're trying to do," McCleod said peaceably. "So, naturally, we want whatever information you can give us about him... You knew his name?"

"I? No, I never. Alice was always pretty close about that. Made me jealous sometimes. But then, she'd been potty about him—letters every day, and that stuff. And them in the same town."

"You don't know anything about him? Tall, short, fat, thin? Old or young?"

"According to Alice, he was the answer to a maiden's prayer. That's all I know."

"You knew she was going to see him, at any rate. Didn't you?"

"I? No, I didn't... I was away that week-end. All I knew was that she was expecting a visit from a gentleman. It had got something to do with it, but I don't know what."

"A gentleman? Who?"

"I don't know. I've told you."

"You know why she went there?"

"Why, of course, to see him, and make him do what was right."

There was an alert expression on her face which convinced McCleod that she had been perfectly aware of the scheme for blackmail; but it was manifestly no use pursuing the subject.

"I understand that she first traced him again through an advertisement in a newspaper—"

"No, she didn't. It was a picture. The advertisement wouldn't have meant anything to her. She didn't know his name—then... She found out afterwards. It was a photograph."

"She didn't know his name?"

"No. That was the sort of soppy affair it was. You'd never catch me doing a thing like that."

"She found out afterwards. When she'd seen the photograph?"

"Yes."

"And then she saw something else in the paper. What was that?"

"How should I know, nosy?... That's your job."

"Who was she expecting this week-end?"

"A gentleman who was going to help her."

"But who?"

The girl made a grimace. McCleod gave it up as a bad job, only trying one final appeal.

"Well, Miss Reade," he said. "I've no doubt that you want what is right done by your friend—"

"I want to see the rotter hanged."

"And so do we—if he's guilty. Then, if you can think of anything that might help, you'd better tell us."

The girl hesitated. "I'd tell you like a shot if I knew. But there were things Alice didn't tell me even, me she was friendly with. And she was dotty about that boy."

"Boy? He was a young man, then?"

"Oh! You know.... A boy's anything in trousers. They never grow up—not till they're dead."

"Do you know how she found out his name? From the photograph, I mean? Was it printed underneath?"

"No, it wasn't, as it happens.... To tell the truth, I helped her. Having a boy friend in the process department of the paper that printed the pictures."

"Then you know the name?"

"No, I don't. She saw him herself. And he only gave her half a dozen to choose from. I don't know how she found the right one."

"Sure there's nothing else?"

"Now, look here!" She glanced at the clock. "Keep me another five minutes and I'll get the push... I've told you. Now why don't you go and get him?"

"Just a minute... How long ago was it since she saw him?"

The girl thought. "Must've been three years or more... Now, good afternoon!"

McCleod was feeling a little depressed as he descended the stairs. He had, not unreasonably, hoped for a good deal more. The reticence of Alice Ridworth and the preposterous way in which the whole affair had been conducted had foiled him, and he seemed to have learnt comparatively little. But he knew now at least the motive for the second murder, and in all probability for the first. He could now place the time of the association between the murderer and the dead woman, or at least fix a limit in one direction. And he had, or hoped that he had, plenty of specimens of the man's handwriting. But as he returned to the dead woman's room and looked at the letters again preparatory to pocketing them he was not so sure. There was something artificial and cramped about the style which suggested a disguise, and as he stowed them away he was quite prepared for a disappointment in this respect.

Helped by the superintendent, he made a further careful examination of the bedroom; but without any result. The copy of The Times had apparently been returned, and inquiry showed that it had since gone up in smoke in the kitchen range. Of the photograph there was no sign. And yet these two provided promising, if troublesome, lines of inquiry. A careful search of the files was bound to show something, and if the girl had obtained the information it should be possible for the police. Too late he went to ask for the name of the process worker; but had to curse himself for his neglect. Miss Reade had already gone out.

As he left the house he had a feeling that the solution of the mystery must be very near, but it still eluded him. Taking leave of the superintendent, he returned to headquarters. From his own investigations and the statements taken by the superintendent there were a number of inquiries which he wished to have made; and in particular, he had to solve the problem of Smith, who still lay heavily on his conscience.

In this respect at least, a brief note from the Assistant Commissioner relieved him. His action in ignoring the burglary was completely endorsed, and the suggestion was even made that he should invite Smith's co-operation in any work affecting the secret poison gas. The reputation of the spy-hunter evidently stood high; though McCleod was a little surprised that red tape should have been cut so easily. As he had no longer any faith in the existence of the poison gas, the help Smith might give did not arise, and he still had sufficient distrust of his opponent not to enlist his aid unnecessarily.

It seemed as though there was little more that he need do in London immediately, however unsatisfied he might be about the results of his morning's work. Glancing at his watch, he decided to walk to the station, and, as he went, revolved in his mind the various points of his recent interviews. Alice Ridworth had lived in the same town as the man connected with the Research Institute for some time about three years ago; she had seen him frequently, had corresponded in some mysterious way which did not seem to be through the post; had finally had some "trouble" and had come to London where she had lost trace of the man. But she could not, he thought, have known of his connection with the Institute, or she would have looked him up before. In all probability, then, the vital photograph was a group of some kind, in which she had identified the man whom she had known. Then another thought came to him. It seemed as though the name attached to the photograph was that of Professor Roseland, and that the girl had written to him. That might have been the reason for the murder of the Professor. Perhaps the news of the murder, or perhaps the fact that Roseland had not replied, had made her pay a personal visit. And yet, somehow, she had contrived to fix an appointment with the murderer.

On the whole, it seemed likely that the same attitude of semi-secrecy had been preserved even during the final stages; neither knowing exactly what the other side intended, or telling what was known. It occurred to him that perhaps the gentleman who was to have come that week-end was Roseland himself.

He was more than half-way to the station when suddenly as if by a miracle, a whole number of odd items seemed to slip together into a complete whole. He stopped in the middle of the busy pavement, pondering over the matter. He was certain that the result was correct. It must be. And yet, in itself it was an impossibility. But he had met the impossible before, and it was with a better heart that he pursued his way to the station.

---

CHAPTER XVII
The Bloodstain

SUPERINTENDENT CARBIS had viewed the temporary departure of McCleod with mixed feelings. On the one hand being left in charge with only Sergeant Ambrose to represent the C. I.D. threw a certain amount of responsibility on his shoulders; on the other, though scarcely jealous of the London detective, he nourished a sneaking feeling that the local staff could do at least as well. It was perhaps partly to prove this that he threw himself into the work with enormous energy.

To his mind, Danton and Wiedermann were still the obvious suspects; and, if Wiedermann's alibi for the Friday was sound, that left him with Danton. But he was taking no chances. By the time he had issued his instructions that morning, either of them would have to be more than ordinarily clever to move a yard without its being reported to him. Smith was another source of anxiety; but Smith was confined to bed as the result of the dog-bite, and watching him was comparatively easy. Thursden, Hope and Boynley he was not troubling about much; and about Seymour not at all. And for particular and personal attention he had singled out Couche.

The attendant that morning was in a distinctly subdued frame of mind. Awaking to find himself in the cells combined with the after effects of what he had drunk the night before to produce a misery which made him tractable, and he answered the superintendent's questions meekly.

On the subject of Couche's night out, Carbis could learn little that was interesting. Everything seemed to have happened exactly as Smith had admitted and, in consequence, neither Smith nor he could be guilty of killing the woman. And regarding the story Danton had told about the burning of the trousers the attendant seemed to be in no condition to put up any resistance. Carbis kept him waiting for a little while, and then looked up at him sternly as he broached the subject.

"Now then, Couche. Mr. Danton's already told us something about what you did yesterday afternoon, and I don't mind telling you that you said enough when you were drunk to make us pretty certain of the facts. It seems to me that you'd better give us the whole story."

"About—?" Couche began as though preparing for a denial; and then gave in. "Yes, sir," he said meekly. "I'll tell you everything. But there's no harm in it, sir. It was just that I got a bit scared—"

Carbis nodded encouragingly. "That's what we thought," he said. "And as a matter of fact your little drunk last night was pretty lucky for you... You know why?"

"Yes, sir. Well, sir, about the trousers... I was more than a fortnight ago that Mr. Hope spilt some acid on them, while I was cleaning up in his laboratory. Burnt quite a patch, sir, it did, just above the knee, and caught his leg a little. And he says they weren't any more use to him, and would I like them, but he'd keep the coat for using in the lab. Well, you see, I do a good deal of dirty work, and under an apron the mark wouldn't show anyway. So I called at his lodgings on my way here next day, and brought them along; but, not wanting to wear them just then I left them here."

"Yes?" Carbis prompted. "And then?"

"Then, sir, when you got to asking who wore a brown coat, I got scared. I thought that I'd do away with them altogether, or at any rate hide them till I saw how things went. I was burying them when Mr. Danton came; I could see he thought it was queer. But I told him a tale about rubbish; and afterwards, just in case it hadn't satisfied him, I buried some rubbish there and made up a couple of other parcels."

"And the trousers?"

"Well, sir, I burnt them in the furnace."

"All of them?" Carbis smiled and produced the fragment. "What about that?"

Couche's jaw dropped. "But I went down again, after I left Mr. Seymour, and there wasn't a sign—"

"Mr. Danton was watching. He picked it out in the meantime."

"Mr. Danton!" Couche flushed angrily. "So he was spying on me, was he? Well, I'd like to know how he stands himself, and I don't mind telling you so. Never a word to throw to a dog, and always so fussy if you happened to move his papers..." He paused. "Why, sir, I shouldn't be surprised if he didn't—"

"But you've no reason to suppose so?"

"Not to say a reason; but when a man looks like he did if the Professor's name was just mentioned—"

Carbis let him go on, prompting him gently from time to time; but it was quite plain that his accusation was founded on nothing more concrete than animosity. No new facts emerged, and at last Carbis dismissed the attendant with his suspicion of Danton strengthened but not his proofs. Hope's part in the affair seemed to be completely innocent. Even if the student had been far-sighted enough to plant evidence against the attendant so far in advance, he would scarcely have given away only a part of the suit, and kept the coat himself. Danton was another matter. He had had a better chance than anyone else of committing the murder the night before; and his conduct had been open to suspicion. He had had no alibi for Roseland's death; obviously disliked him, and seemed to have had as good opportunities as anyone still on the list of suspects. He was still wondering what his next move should be when the telephone rang. Sergeant Ambrose was at the other end.

"If you've a moment to spare, sir, there's something here I'd like you to have a look at."

"Here? Where's that?"

"I've been making a further examination of the scene of last night's affair. We've found something—I'd just as soon not go into details over the wire... Could you manage to come and see it, sir?"

"Right. I'll be with you in five minutes."

Much as his curiosity had been excited, Carbis was in agreement with the caution of the sergeant. Though the secrecy of the post office is ordinarily inviolable, cases have occurred when people have been tempted to break it, and, judging by what had already appeared in that day's papers, the inducement to do so might be considerable. But principally he was puzzled to know what Ambrose could conceivably have found. The search last night had been thorough enough; and he himself had gone over the ground first thing that morning; though he had allowed the sergeant to continue his own investigations farther afield. It must, he decided, be something not on the actual scene of the crime, but dropped by the murderer some little distance away.

Ambrose met him by the white gate, near the area which was still carefully fenced off around the tree.

"It's a little way up here, sir," he said. "In the garden of the house, as a matter of fact.... Of course, it may be nothing—"

"But what is it?" Carbis asked impatiently.

"Well, sir, I suppose it will have to be tested. But unless I'm very much mistaken, it's blood, sir."

"Blood!" Carbis echoed. "But—last night... there wasn't any possibility of blood."

"No, sir. And as a matter of fact, in my own view, it probably wasn't... But perhaps you'd better see it yourself first, sir?"

Carbis nodded, and Ambrose led the way up the drive. They reached and passed the place where the road to the house diverged, and they were only a short distance from the laboratory itself when Carbis was moved to protest.

"Why, where on earth are we going? Even if there was blood here, what could it have to do with last night's affair?"

"That's just it, sir. I don't believe it had anything." He paused for a moment. "But Professor Roseland bled a little, sir."

"Roseland! But he never left the laboratory!"

"Perhaps not, sir... It's just here, over the fence."

Only a couple of wires, giving protection to a growing hedge, barred their progress, and, following the sergeant, Carbis found himself at the top righthand corner of Roseland's garden, only a short distance from the path which connected the laboratory with the house. This part of the ground had been laid out in rockeries and sunken paths, and the work had obviously not been done long, for the stones still glistened a fresh yellow. Ambrose stepped down into one of the sunken paths, and went round to the far side of one of the heaps, where the way ended in a cul-de-sac. He stopped and pointed.

"There, sir."

Almost at the first glance Carbis knew that the sergeant was right. He did not profess to be an expert on bloodstains, but there was no mistaking the blackish-red discoloration on the last stone of the pavement. The mark was not big; no more than a couple of spots joined together, and about as big as a half-crown. But it was undeniably blood. The thought crossed the superintendent's mind that it was a tribute to the thoroughness with which Ambrose had searched that it had been seen at all.

"Of course, it might not be human blood," Ambrose admitted. "That would have to be tested. And it might not have any connection with the crime if it was, sir. Someone might just have cut a finger gardening, or something."

But it was plain enough that the sergeant did not believe his own objections. Neither, for that matter, did Carbis. It might be unreasonable, but he felt certain that there before him lay a clue to what had happened. And yet, if Roseland had been killed in the laboratory, and if his head had struck the bracket, it could not be his blood. The murderer's, then? It seemed in the highest degree unlikely that there had been enough blood shed, considering the absence of any struggle. There was, of course, the broken glass. If the murderer had cut himself, it might account for what they had found. And he suddenly remembered a bandage on Danton's finger that afternoon.

"You'd better look after it, Sergeant," he suggested. "Photograph it; then take the whole stone up. You can scrape a bit off for the doctor to look at— Hullo! What's that?"

He bent down to look more closely. It was only the smallest possible trace of something on one of the stones of the rockery, and at the first glance he had thought that it was a bit of moss. He examined it more closely; then made way for Ambrose.

"It looks like paint, sir," the sergeant said in a rather bewildered voice. "It's quite dry. More a chipping off than a smear."

"Yes," Carbis said thoughtfully. "It's paint... Right. I've an idea... Would you carry on here? Look after that paint as well... I think somehow..."

He left the sentence unfinished and turned slowly along the path. Without quite understanding the significance of the latest discoveries, he had a feeling that they must be tremendously important. He went over the various possibilities in his mind; the broken glass, Danton's cut finger, the wound on Roseland's head... But there was the paint as well. Where could that have come from, and how could it have got there? If Roseland had been murdered in the laboratory, could the blood have anything to do with the crime, after all? And Roseland must have been killed there; or at least, the wound on his head had been inflicted there, and in this case it was the wound which was the vital factor. The more he thought about it, the less likely it seemed that Roseland could have put up any resistance, or in any way have injured the man who had killed him... And then the truth burst upon him overwhelmingly, and he broke into a run.

Percher, on duty in the lodge, was amazed at the haste of his superior as he burst in breathlessly through the door. He hurried out.

"Find me a screwdriver—quick!" Carbis ordered. "Bring it along to Roseland's room as soon as you can. I suppose that there's one there?"

"I think so, sir. In the basement somewhere—the workshop. I saw it—"

"And that's a point, too... Right. Hurry."

When Percher went in search of him with the tool in question he found the superintendent on his knees beside the bracket which still bore the mark of Roseland's blood. He was examining it attentively, and motioned to the detective to come to him.

"Look here, Percher," he said, "you know, I suppose, that this mark doesn't correspond with his having hit this thing in any ordinary way? Well, you can see, anyway. He'd have to have been lying down—and there's hardly room to do that and get up with enough force to break his head. And, so far as one can see, the blood hasn't been just smeared on afterwards; besides, if anyone had done that, he'd have done it properly, and put the mark on top. That's right?"

"Yes, sir," Percher assented, dangling the screwdriver between his fingers. "But—"

"What's the answer? Well, we had thought that someone picked him up and knocked his head against it. That was possible, anyway, though it must have been done in a most awkward way. But the more you think of it, the more absurd it seems—all the more since now we're practically certain that Roseland wasn't poisoned, but died naturally, or from the blow on the head. Well, what's the solution?"

Percher only shook his head. Carbis smiled triumphantly, and dug his thumb-nail first into the paintwork of the wood to which the bracket was screwed, and then into that of the wall.

"Try it yourself!" Carbis commanded.

Percher obeyed. The difference was obvious at once. The paint on the wood, though otherwise indistinguishable, was markedly softer than that of the wall. But he looked up without comprehension.

"Don't you understand?" Carbis demanded. "Give me that screwdriver— No. We'll try another first."

He jumped to his feet and led the way from the room, and with Percher following a little dazedly in his wake, made his way along the corridor to Hope's laboratory. Here, too, there was a bracket of a precisely similar type, and Carbis tested it as he had done the other; then nodded to the detective.

"Try this yourself," he said. "Notice anything?"

But even before Percher dug his nail into surface the difference was obvious. There was no corresponding softness in the paint on the wood.

"Lend me that screwdriver."

There were four screws holding the bracket, and even after he had scratched the paint away from their heads they proved surprisingly hard to move. In order to guard against loosening with the vibration of the spindle they had been screwed very tightly home, but as he got the first one out it was plain that this was not the only reason. The steel had corroded slightly, no doubt owing to the peculiar atmosphere of the laboratory. Carbis grunted with satisfaction, pointing to the numerous scratches which the operation has caused round the screw-hole. In a few minutes he had extracted the last screw, and the bracket fell to the ground. Carbis picked it up by the end which had been attached to the wall; but still Percher did not understand. It was only when the superintendent rose to his feet and flourished it that the truth flashed upon him.

"You mean—?" he cried.

"You could knock anyone out with this—eh?" Carbis asked. "And in the hurry of the moment, particularly if it was dark, you mightn't remember that he had to be hit with the side which was going to come uppermost... And the balance is a bit awkward, and you mightn't make a very good job of it—just a slight glancing blow, like Roseland had."

"Good Lord, sir!"

"It's not surprising that we never thought of it. When a thing's fixed to the wall, one tends to regard it as a fixture—as something that can't be taken away. You think a person might hit it, but you don't think someone might have been hit by it. And, when Roseland was dead, all that was necessary was just to screw it back again and repaint. After all, there's quite probably paint about the place—"

"There was, sir—where I got the screwdriver."

"It had got two days to dry in, and it did dry—well enough to escape notice, but not quite well enough to be uniform with the rest.... You can see the mess I've made round the screws. He'd got to cover that up somehow."

"But why, sir? If Professor Roseland was murdered in the laboratory—"

"And that's the whole point—he wasn't!"

Percher's jaw dropped comically; but Carbis disregarded him. He went on, speaking almost to himself.

"There always was the difficulty about how anyone knew Roseland was coming to the laboratory that night... And the answer is that he wasn't, and he didn't—at least, not alive. He was murdered in the garden as he was on his way to the station to go to London. And the murderer forced the window, put him in here, and made everything look as if it was inside that Roseland had been hit—or rather, he tried to make it look as if he'd been poisoned. And that, unless I'm very much mistaken, explains—" He broke off, seized the bracket and the screwdriver and made for the door. "We'll try Roseland's now."

But in Roseland's laboratory the removal of a single screw seemed to satisfy him. Unlike those which they had taken out in Hope's laboratory, it was still bright and shining. The superintendent eyed it with satisfaction.

"See the difference?" he said. "He had to use new screws. I wonder what happened to the others? Maybe we'll find them... Have they sorted out those waste boxes yet?"

"Not yet, sir, I think."

"He might just throw them away... Or he might pocket them, and get rid of them later... We'll hope for the best. You'd better lock Mr. Hope's room and see that no one goes in there. If the murderer noticed we'd unscrewed the bracket, he'd know that we were pretty well on his track—"

"But who is the murderer, sir?"

The question took Carbis a little aback. He had been so elated by his discovery that he scarcely tried to work out its exact bearing on things in general. The detective's question pulled him up sharply. The murderer was certainly the man who had unscrewed the bracket, but how much further did that get them?

"Well, this rules out one difficulty, and gives us some more lines to cover," he said a little vaguely. "We might find the screws in some place which would prove..."

The sudden dashing of his hope depressed him. He had almost been picturing himself as handing over the murderer to McCleod on his return with everything proved and settled. But, after all, was he much nearer? He stood looking vaguely round the laboratory. His eyes lit on the pile of broken glass, from which the larger pieces containing Thursden's prints had been removed, and one idea brought another.

"Percher," he said, and indicated the pile. "There's another job for you! Just for something to do—and to save you hanging about idle in the lodge..." Carbis grinned devilishly. "I'd like you to put that together!"

"Put it together, sir?" Percher almost groaned.

"Yes. Nice little job—like knitting or doing a jig-saw!... No, I'm not joking. The point is this. If the body was brought here, why not that? It's one thing people are always scared about when they're doing burglaries or anything—breaking glass, particularly at night. If you'd just murdered someone, would you take the risk of a smash like that, on the scene of action? I doubt it. If that had to be smashed, you'd smash it quietly somewhere beforehand, and bring it here. And—" He broke off and paused. "It's a chance, Percher, only a chance. You might not get all the pieces!"

From Percher's expression it was plain what he thought both of the chance and of the task which he had been given. He opened his mouth to say something, but, perhaps fortunately, he never said it. The telephone whirred suddenly. Carbis looked at it in surprise.

"Hullo! This is through, then?"

"Yes, sir. I plugged it through before I left the lodge, knowing that we were going to be here."

Carbis nodded as he lifted the receiver. "Superintendent Carbis speaking... Who's that? Oh, from the station. Yes, Inspector?"

"We've a message here from Inspector McCleod, sir. He said it was urgent. He's coming back by the two o'clock train, and he says he thinks he's on to something... He asks you to keep a special watch on Roseland's house— That's all, sir."

"Didn't he say who?"

"No, sir."

"Right. I'll see the man there." He paused. "Oh, and you might send someone else along. They're pretty busy here.... You can spare one?"

"Yes, sir." There was resignation in the inspector's tone. The resources of the police personnel had already been strained. "I'll see to it, sir."

"That's good."

Carbis felt a little chagrined as he replaced the receiver. He had been so sure that he had for once managed to put McCleod in the shade, and now, apparently, the inspector was coming back with the murderer ready in his pocket. But McCleod's message had been vague enough. Probably, after all, he had no more than a strong suspicion. He smiled.

"Well, we'll see which wins!" he said.

---

CHAPTER XVIII
Danton Remembers

IT was habit as much as anything which caused Danton to set out for the Institute at the usual time next morning. Work was out of the question, but as long as the police allowed access to the laboratories even the pretence of doing something was better than waiting in one's lodgings, or walking the streets in the certain knowledge that one was being shadowed. Of his supposed follower he did not catch a glimpse; but he found the sensation of being watched peculiarly irritating, and felt an impulse to lie in wait somewhere to deal with anyone who might be behind. He was glad when at last he turned up the lane to the Institute where the police would at least be in plain view. Thinking it over, he decided that that was partially at least his motive for coming. Although the police were not likely to give anyone away, one was at least in the middle of things.

Beyond the white gate a constable guarded the road, keeping at bay the little crowd of morbid sightseers trying to obtain a view of the scene of the tragedy; but he let Danton pass on, learning his name. Here, for the first time, where the bare lane offered no hope of cover, he got his first sight of the detective who was tailing him, and even though he had known the position, the proved fact rather appalled him. He found himself thinking of Boynley's suggestion of the night before that he should turn detective to prove his own innocence; but at the thought he laughed a little bitterly. In view of the results of his previous effort, he felt that any further attempt would probably end in his being hanged on Seymour's wedding day.

Nevertheless, he stopped to look for a moment at the roped-off space round the tree. Someone had poured plaster into the two footmarks and, presumably, was waiting for them to dry. Danton had not noticed them the night before, and now that he came to look at them, emphasised by their white filling, the oddness of their position struck him strongly. He forced his mind back to the events immediately preceding the scream, trying to visualise exactly what had happened. It had been too dark to see very clearly; but the woman had certainly stopped here. That was why he had been so close upon her at the time of the murder. She had been standing by the tree, perhaps to wait for someone. But the position of the prints seemed to be a denial of any such explanation. The toes were pointing towards the tree. She had been facing the tree, then, and at a slight angle to it when she had died; but if she had been waiting for anyone she would surely have been looking up or down the road. He was still pondering over the mystery when a gruff voice behind him made him turn.

"Morning, sir."

It was Sergeant Ambrose who had spoken, and he was eyeing Danton with an expression which might have meant anything. He had evidently been astir early, for his boots and trousers were soaked with the dew from the grass on which he had been walking. The sight of several police still searching along the hillside explained what he had been doing.

"Good morning," Danton answered, trying to make his voice sound as natural as possible. "I was just going up... I suppose there's no objection?"

"None, sir. The passage leading to the library and Professor Roseland's room is closed, but that's all, sir."

"Thought I'd be as well there as anywhere else. And it will save you trouble. I shall be under your eye there, anyhow." He glanced back at his follower, who was pretending an interest in everything else in the immediate neighbourhood. "Though I suppose I'm under your eye already?"

There might have been sympathy in Ambrose's face as he answered: "I shouldn't let that worry you, sir. Why, half the people one's got to watch turn out to be perfectly innocent; only one can't be sure... I understand that you were doing some detective work yourself, sir?"

Danton smiled. He guessed that the sergeant was trying to entice him into an innocent conversation with a view to trapping him into a false statement. Well, he was at liberty to try. Danton determined to fall in with the scheme.

"It doesn't seem to have been an unqualified success," he said dryly.

"No, sir? But at least you were quite near her when she died. It's odd you never saw anyone, sir."

"I saw, and felt, Mr. Wiedermann immediately afterwards."

"Yes, sir. But before?"

"No." Danton dropped any pretence of flippancy. "I thought I heard something just before; but that was probably Miss Roseland or the inspector... In front, I don't think I even heard Wiedermann coming."

There was the slightest flicker of the sergeant's eyes, as though he found the last statement interesting.

"And I suppose you saw her standing there, sir? You've no idea what she was doing?"

"It was too dark... As a matter of fact, I was just wondering about that... Those footprints show up very clearly. What could she have been doing standing there in the mud almost facing the tree like that? Of course, she might have been looking over the hedge—"

"She might, sir," the sergeant agreed without enthusiasm, "but it's a pity you didn't see. Now, try to take your mind right back, sir. Was she bending down, say, like this?"

Climbing over the rope, Ambrose assumed an attitude by the tree, taking care to avoid the footprints. He pretended to be tying his shoelace; then stood up, looking at Danton inquiringly.

"No, I'm quite sure she wasn't," Danton said positively. "The one thing I could see was the outline of her head against the sky right up to the time she fell down."

"Like this, then?"

This time the pose was suggestive of a woman tidying her hair, and in the unfeminine medium the sergeant presented it would, under other circumstances, have been comic. Danton considered.

"Yes, that's more like it. I shouldn't be surprised if that was it... And if she'd got an appointment with anyone here, it would be quite natural, wouldn't it? Even though it was dark."

"It would, sir. Especially for a woman. You'd be surprised how they'll tidy their hair under any circumstances. It's all a matter of habit."

"For that matter, I suppose this meeting-place is an instance of the way one's mind works on conventional lines. It reminds me of a picture I've seen—'The Trysting Tree' or something—one of those sloppy romantic things—"

"It wasn't very romantic for her, poor girl." Danton stared a little at the note in the sergeant's voice. He would scarcely have expected the policeman to nourish the finer sentiments. "But we'll get the man that did it, sir."

Danton wondered whether or not there was a threat in the last words, and decided that there was not. It seemed as though the sergeant had decided to acquit him, and his spirits rose a little. He felt tempted to venture a question on another subject which had been on his mind most of the time since he had first awakened.

"I suppose you haven't seen Miss Roseland?" he ventured, and found himself colouring unreasonably under the sergeant's mild eye. "I just wondered how she was. Last night must have been a terrible shock—coming after her father's death—"

"Yes, sir," the sergeant agreed without emotion, "I saw her about half an hour ago." He glanced across the road to a stile which marked the continuation of the path through the white gate. "She went along the hill there, sir. With the dog."

"Oh, the dog?" Danton attempted to be casual. "It's better, then?"

"Seemed fresh as a daisy this morning, sir... More than Mr. Smith's leg is, I'm afraid."

There was a sort of grim satisfaction in his voice, but Danton scarcely noticed it. He was looking along the slope.

"Along here," he repeated.

"Yes, sir. With Mr. Seymour."

"Mr. Seymour? Oh."

The bleakness of Danton's voice was not lost on the sergeant.

"But Mr. Seymour came back a few minutes ago, sir," he said, and refrained from adding that the demonstrator had looked in a worse temper than he had ever seen him in before. "I think he was worried about something, sir," he said, offering a gentle hint.

"Worried?" Danton's spirits rose; then sank abruptly. "I should have thought I'd more cause than he had," he said grimly. "He's got an alibi both times."

"Yes, sir." The sergeant shaded his eyes. "I think that's her coming now. If you went along, you could meet her, sir."

Ambrose's face was perfectly innocent; and in any case, Danton was not looking at him.

"I—well, I might as well," he said, and then remembered his watch-dog. "Oh. But how about—"

The sergeant interpreted his glance down the road correctly.

"Well, sir, he can see you for miles," he suggested helpfully. "And, strictly speaking, you shouldn't know he's there, so I shouldn't trouble about him."

Danton laughed in genuine amusement. Sergeant Ambrose's attitude appealed to him. He raised a hand quite cheerfully as he Set off across the short grass. It was perfectly natural, he told himself, that he should ask how she was, in view of all that had happened the night before; but as he went his courage began to evaporate. He would have changed his mind, but, glancing back, he saw the sergeant and his watch-dog in careful consultation.

There was certainly nothing wrong with the dog which came bounding along the track towards him; and being among those who think the Alsatian a vastly maligned animal, he extended a hand and patted it. It was still jumping round him as Sylvia drew near, and he was grateful for the opening it offered.

"The dog's all right," he greeted her. "It wasn't much hurt, then?"

"Oh, no." She smiled. "He was only drugged, though last night I could have killed whoever it was who did it."

Apparently she had not been informed about the identity of the burglar; and Danton felt a passing wonder at the treatment accorded to Mr. Smith, but did not trouble himself.

"You're looking better—you're looking splendid!" he said, and it was a sincere compliment; for the sun shone on her hair and the morning air had put colour into her cheeks. Even her eyes had lost something of their hunted look. "It was jolly sensible to get out—"

"Oh, I had to!" A shade seemed to pass over her face; then vanished as she looked over the pleasant, green expanse which lay stretched below them. "After London, this is heavenly!"

"Well, it's a matter of point of view," Danton said. "I've been here two years—rather more; and I won't tell you how many times I've wished that I was in London!"

"How could you?" Her eyes sparkled as she looked. "It's the loveliest country in the world."

"I suppose—you know, I'd no one here that I was particularly friendly with. I didn't seem to get on with the others—somehow. They weren't my kind, and in a place like this, you see so much of each other—"

"Not even Hope? I don't see how anyone could dislike him."

Foolishly enough, Danton felt a tiny pang of jealousy. And then he remembered Seymour. It was strange that she should have referred to Hope instead of the man to whom she was engaged. He was silent.

"I like Hope, myself," she went on, and there was a suggestion of doggedness in the way she spoke. "He's not terribly brainy, outside his work, and he never works any more than he's got to, but he's a decent, normal sort of person. He's not moody, and queer, and exacting—"

The implied criticism against someone was clear, and Danton was wondering whether it was against himself or Seymour. She looked at him and evidently read something of his thoughts; for she flushed crimson. She stopped, facing him defiantly.

"I suppose you think I ought not to talk like that? But Francis is all that... I thought that I loved him, and I've tried hard to—"

"Look here, Miss Roseland," Danton said, though he found it difficult to speak the words. "You're upset with what's happened... I quite admit that it would be idiotic to marry anyone you felt like that about, but you won't. When things settle down, it will come all right again. The great thing just now is to avoid doing anything—anything—"

"That I might regret!" She finished his sentence for him, and laughed bitterly. "That's what my uncle said."

"Well, I didn't mean to speak to you like an uncle," Danton said humbly. "But, you know, it is a fact. When people's nerves get worn beyond a certain point, they do things that they wouldn't at any other time. After what you've been through—"

"That's it... It was before—before all this... I've known that it was going to happen—oh, for weeks. But when you've promised anyone—and it's so hard to know... It was why I came out this morning—to get right away from things and think things over. And then Francis insisted on coming, and I expect I was rude to him. He was in a dreadful temper when he left... You didn't meet him?"

"No. It was the sergeant who said where you'd gone." This time Danton coloured. He had been led into a confession that he had followed her deliberately, but she seemed to pay no attention. "And he said that Seymour had come back."

"He should never have come... I didn't want to be cruel; but I had to get somewhere alone..."

Danton felt uncomfortable. "I'm sorry," he said, "I wasn't sure whether to come or not. I never thought—"

"Oh, I didn't mind your being here.... The very fact that I'm talking to you like this ought to show you that."

She gave a quick smile which vanished almost at once. "You know, I think I wanted someone to let off steam on. I'm feeling better for it."

"And I'm no worse!" Danton smiled. "But if you like I'll go."

"We'd better both go... Prince! Here, Prince!" As the dog came bounding towards them, she turned her face towards the laboratory with the air of someone who steels herself to an effort. "My uncle worries if— Of course, that's natural."

They walked in silence for a little distance. Then she looked up and caught his look of frank admiration.

"You do look better, you know," Danton said a little hastily. "Don't you feel as if the air had blown away a whole host of cobwebs and fancies? When you get back—"

"Even you're trying to make me change my mind again." She bit her lip. "It's been hard enough to do, but I know it's right... I can't go on with it. When I get back, I shall find Francis and tell him."

She spoke with a quiet decision which left Danton without a word.

"It's no good you or uncle or anyone trying to make up my mind for me," she went on. "I've got to do it myself. And, when I've done it, you've no right—"

She paused. Danton was staring ahead to where the sergeant and his watch-dog were awaiting their return.

"No," he said slowly. "I wish to God I had."

The words had escaped him almost without volition. It was only in the silence which followed that he realised what he had said.

"I'm sorry," he said. "I didn't mean to say it... But I don't care."

There was a long pause. They were only half a dozen yards from the stile.

"And I didn't mind," she said gently; then, before he could speak she called. "Here, Prince— Prince!"

She stooped to put the lead on to the great dog's collar.

"Well, good-bye, Mr. Danton—" She began in what was evidently intended as his dismissal.

"Just a minute," Danton said bluntly. "You meant that? About Seymour?"

"So much so that I'm going at this minute to tell him. No, he won't be back yet. In twenty minutes or so... It's no good objecting—

"I don't object," said Danton, and took the dog for a moment as she mounted the stile. "I'm glad."

Without replying, she accepted the dog's lead and with a smile to the sergeant set off up the hill. He watched her for a few minutes; then turned to meet the sergeant's eye.

"She's a nice young lady," said Ambrose approvingly. "And that's the way to take it. No good lying down and moaning. But she looks—well, as though she was going to take a high dive."

"Perhaps she is," Danton said, and left him.

He saw Sylvia Roseland turn off the drive towards the house, and in a few minutes she was hidden by the bushes. Near the top of the path a second constable seemed to be on guard over nothing in particular, and Danton looked at him curiously before he went up the steps. It was, of course, the merest mockery even to try to work. He kept turning things over in his mind and, strangely enough, it was not on his own danger that he felt himself dwelling, but on the interview which he had just had.

More than ever he was convinced that he loved the girl; and if she had really made up her mind to tell Seymour, one obstacle was removed. He tried to tell himself that he was not biased in approving of her decision, but knew perfectly well that he was. He was sitting on a stool by the bench with his head in both hands trying to work out what was best to do, when Hope entered breezily.

"Hullo, Danton!" he said. "So you've decided to brave the chamber of horrors. The others haven't turned up yet—and the place would be lonelier than the North Pole, if it weren't that one fell over a policeman whenever one goes quickly round a corner... What's the matter with you? Thinking which paper will pay best for your full confession?"

But Danton did not respond. Abruptly the knowledge of his own position seemed to overwhelm him with renewed force.

"'Why so sad and mute, young lover—?'" Hope began, and Danton looked up angrily.

"What the hell do you mean?" he snapped.

"Why, nothing—nothing... Look here, old boy, did you ever know me to say anything that meant anything? If I've done it by accident, I'll grovel. There!"

"Sorry." Danton smiled a little. "I oughtn't to go off like that. But, you see, you're all right. And when I think about things—"

"Yes, it's hell," said Hope uncomfortably. He seemed to search for something to say; and then, failing to find it, started to whistle. He had only got through a bar or two when Danton started to his feet.

"What's that?... Good Lord!"

"Sorry, old boy," Hope said contritely. "I really didn't mean—"

But this time Danton was not annoyed. He was staring out of the window in the direction of the scene of the murder.

"'I sent a letter to my love...'" he hummed, and stopped. "Damn it! I knew it was a picture! One of those ghastly things in my digs in town—but it wasn't 'The Trysting Tree.' It was 'The Love Letter'."

Hope was looking at him as though he was demented.

"What d'you mean, old boy?" he asked.

Danton grabbed his arm, dragging him from the room.

"Come on! We've got to find that sergeant chap—or the superintendent—"

"But, I say, you..." Hope protested; then reluctantly accompanied Danton out of the front door and down the drive.

The search for the responsible police did not prove to be difficult. Both Ambrose and Carbis were standing a little way down the drive, apparently in consultation. They looked up in surprise as Danton bore down upon them, with Hope trailing unwillingly in his rear.

"Sergeant, I've thought of it!" Danton broke out. "What she was doing—why she was standing there—facing the tree!"

Carbis merely looked his surprise; but Ambrose was imperturbable.

"Yes, sir?" he asked. "You've thought of it—"

"I knew that the business reminded me of one of those awful pictures. And the one I thought of was one showing a girl by a tree waiting for her lover. But that wasn't the one... Sergeant, have you searched the tree?"

"Searched the tree, sir?" Ambrose glanced down the drive to where it was visible. "Well, sir, no one could hide in the tree."

"I don't mean that... If my guess is right, there wasn't anyone there when this second murder was committed. But it's an old tree, and pretty rotten. Perhaps there's a hole of some sort—"

"Well, there is..." Carbis began, but Ambrose was already hurrying down the road. They overtook him only when he was standing beside the tree, stretching up one hand to the narrow hole which showed in the rough bark. He looked round inquiringly.

"That's it!" Danton exclaimed; then, as Ambrose was about to insert his hand into the crevice he jumped forward and gripped it. "Don't! Careful, for God's sake!"

The sergeant's eyebrows went up slightly, but he allowed himself to be pushed aside. Danton looked at the base of the tree. A couple of stumps offered sufficient foothold, and in a minute he was looking down into the crack. A gleam of white showed, fairly well down.

"There's something here!" he said; but did not at once put his hand in. Instead, he examined carefully every side of the rotting wood before he stretched his hand out. "It's all right, I think..." he said.

Holding a folded piece of paper gingerly by one edge, he slipped down, and held it out to the superintendent. Carbis accepted it in some bewilderment. Automatically he unfolded it and straightened it out. Then he looked up.

"There's nothing on it," he said, but Ambrose thought differently. As the light from where he was standing caught the sheet sideways, he had seen, not writing, but the indentations left by a pencil when the sheet above has been used.

"There's something..." he said, and took the sheet. "I can't make it out... Chemical stuff? 'C 16 H—something or other—"

"Let me look!" Danton asked, and took the sheet. He studied it for a moment carefully, and a strange expression passed over his face. "Hope!" as he looked up.

"Yes, old boy?"

Danton's face had suddenly become hard. He held out the paper.

"Hope," he said quite softly, "do you recognise this?"

---

CHAPTER XIX
The Dart Again

WHEN Sylvia Roseland returned to the house her mind was made up. Perhaps her conversation with Danton on the hillside had been a decisive factor; perhaps it had only hastened the inevitable. She was in no mood to weigh her motives; she only knew that the thought of being bound for life to Francis Seymour was intolerable; that she could not endure the continuance of their engagement even for another day. In some ways it was a relief that Seymour was no longer suspect; for if he had been, she would not have felt justified in deserting him. As it was, Seymour at least was beyond suspicion for either murder, and she felt free to speak her mind. She knew that it was no sudden decision arising out of the strain to which she had been subjected during the past twenty-four hours. Even before the engagement was announced she had been doubtful; but Seymour's vehemence had overwhelmed her, and there was a natural reluctance to go back upon her promise while any hope remained. Now, she only wanted to get things over as soon as possible. There could be no going back, and no staying where she was.

But, though she had decided to take the plunge, it was to prove more difficult than she had expected. She had assumed that Seymour, after his rebuff on the hill, would have come back to the house; but she could not find him. As she glanced for a second time into the library where her uncle was sitting bowed down over his papers, he looked up with some curiosity; then something in her expression made him rise to his feet and come towards her.

"You were looking for me, my dear?" he asked.

She shook her head. She felt torn between the desire to confide in someone and her inability to brave any possible opposition until she had done what she intended. Boynley eyed her for a moment, and the slightest trace of a frown gathered on his face. Then he smiled.

"Of course, you would want Francis? I'm afraid, my dear, he came in about half an hour ago, looking rather upset. He went to the laboratory... You want him?"

"I—I did want him," she faltered. "There was—there was something I was going to talk over with him."

Boynley did not say anything immediately. He stood looking at her, and his eyes were full of sympathy.

"Sylvia, my dear," he said, "can't you tell me? As your uncle..."

But she could find nothing to say. She stood there miserably, on the verge of tears, but with her resolution unshaken.

"My dear," Boynley came forward and took her arm gently. "I know... I've been expecting this—for some time. Naturally I couldn't interfere, as long as there seemed to be any possibility of things changing—and yesterday, I thought that they had... But I think that you are right. Francis Seymour would never make you a husband. I have thought so for some time. You had better tell him and end the suspense as soon as possible."

"You know?" She looked at him in surprise. "But—but uncle, I've never said a word—I've hardly dared to think about it. Only for this last day or so. And I thought that I'd pretended so well; I hoped that things would change. It seemed to me that one day I should see in Francis again all the things I had seen when—when he first said he loved me. But it's been the other way entirely. Every day he seems less and less like... Uncle, I know I can't go through with it. I hate myself for it, but I can't—"

"And why should you?" Boynley asked with an air of patient reasoning. "You may think, my dear, that as an old bachelor I'm not qualified to express an opinion; but it seems to me that in marriage you cannot afford to build upon a false basis. Admittedly, some people can, and achieve a moderate success. But they expect less. It would be no use, Sylvia, for you to marry where you did not love. That way would be certain disaster. And you have to ask yourself, would it even be fair to him to go on?... You were looking for Francis to tell him now?"

"Yes," she said, and paused. "But, Uncle, you know how it will be. Francis is so—so desperate. I know that I can't face it; but I know that I can hardly bear to face him to tell him so... I don't know what to do. I only know that it has got to end."

"I'm sure, my dear, that it should never have begun.... And now..." He stopped for a moment, and looked down at her. "Now—I may be an impertinent old fool, but isn't there another reason? You mustn't be angry with me, Sylvia..."

She buried her face for a few seconds in the sleeve of his coat, and when she spoke her voice was hardly more than a whisper.

"Yes," she said. "Yes. There is... This morning I was sure of it. I met him... on the hill... But—but... it's so impossible. And probably he's scarcely noticed me—"

"My dear, he's not quite such a fool!" Boynley smiled a little as she stiffened indignantly. "A little young, a little shy, a little too prone to take himself and the world too seriously... But all faults on the right side. He may only have known you for a day, but Paul Danton loves you..." He felt her start, but went on imperturbably. "And he is much more suited to you than Seymour could ever be... Sylvia, this has got to be settled. Go to Seymour's study. I will go across and send him to you."

"Uncle! Oh, Uncle!"

She could say no more, but buried her face in his shoulder and sobbed. He waited for a moment until the sobs gradually died away; then he gently disengaged himself.

"There, my dear. Do as I say. I'm sure that it's for the best..."

Without another word he turned and left the room. Sylvia heard the front door close behind him. But for a minute or two she did not move. She stood staring out of the window over the sunlit expanse of the Downs, and somehow the sight, bringing back a memory of her talk with Danton, seemed to give her courage. She went slowly along the passage to the study.

But, once there, the old hesitations and doubts seemed to revive with renewed force. There was so much in the room to remind her of the days when she had thought Seymour the one man in the world; books, photographs, all kinds of personal details which seemed to afflict her with recollections of their first meetings. In a mood of something like renewed tenderness she opened an album of photographs which stood on the desk beside the weightier papers which comprised Seymour's next thesis. And the fact of its being there was like a stab. Seymour had thought of her even while he was doing the work which had sometimes seemed to be so much more important to him; and now she was going to hurt him.

She turned the pages idly. Francis, she thought, belonged to that minority of men who like being photographed. The album was more full of himself than of anything else; though on every page a snapshot of them together brought her a new pang. Then one of the prints caught her eye merely by its oddness. She did not remember ever having seen it before; but at the first glimpse it looked like Seymour in duplicate. Underneath, in Francis's writing, there was the description: "Whitley and I." She found herself looking at it. Of course there was no real likeness between them. But they were of the same build; they were dressed precisely alike, in the big coat and rather enveloping hat which Francis affected. At a casual glance they were almost indistinguishable.

She stared at the photograph, with a suspicion forming somewhere in the background of her mind. It was a long time since she had seen Whitley... But Francis had seen him recently. She remembered that he had said he was coming down for the day—on Friday morning; and that they were going out for a drive in Whitley's car. Friday—the day of her father's death; when Seymour had left by the early train, and had thereby given himself an unimpeachable alibi. As she looked, the doubt formed and took shape. She remembered the details of Danton's story about his investigations. After all, had the booking-clerk, or the ticket-collector, identified Seymour? Or had they merely noticed a type of hat and coat which, in that town, was unique? She was still staring at the print in horror when the door opened. Seymour stood on the threshold.

She dropped the book guiltily; she looked at him, and her gaze was unflinching. And as she looked, certainty was born in her. She did not know how; but she was certain that Seymour was the murderer of her father. For a minute or two they faced each other in silence. Seymour screwed up his eyes nervously, and shifted. He cleared his throat before he spoke.

"Well, Sylvia?" he asked. "Your uncle said that you wanted me... Naturally, my dear, I am busy... If it is about this morning... Well, Sylvia, did you treat me quite fairly? Of course, I can understand how you feel—"

He had been speaking quickly, nervously, as though unwilling to let her reply. But the flow of words stopped abruptly. His eyes fell to the book of photographs on the table, and as they returned to her face there was a new expression in them, something that she had never seen before. For the first time she felt afraid; her throat seemed to have gone dry. It was a minute before she could force herself to speak.

"Francis—Francis, I came..." Then she was suddenly calm. "Francis, it was about this morning—partly, and about us. I had to speak to you."

Seymour eyed her darkly. Then he spoke a single word.

"Danton?" he asked.

"No—that is, it wasn't. I knew—I have known for weeks. Francis, it's no good our going on with this... It never could have been... I don't love you. I—I've got to end our engagement."

Seymour was still looking at her with a kind of fierce inquiry.

"Danton," he said again. "It is, isn't it?"

"I tell you that that's nothing to do with it!" she burst out almost irritably; but she could not utter the denial. "It—it's you and me, Francis. We couldn't get on together. We couldn't ever be—what we should be to each other if we married."

Seymour's eyes dropped again to the photograph album. Then he looked up at her. There was a frantic appeal in his face, and yet there was something more dangerous.

"From the time I met you," he said slowly, "I only wanted you. I was ready to do anything, to risk anything... I have done, and I have risked—more than you know. There was nothing which I could allow to stand between us—no one. I was happy in my work. Why had you got to come into my life? Why had you got to make me—" He broke off. "I did nothing that I could help doing," he went on more slowly. "I have been—compelled... Nothing had to come between us..."

His voice trailed away; but his eyes again dropped to the album. She felt a sudden courage, a desperation beyond her real strength. Her hand went to the book; her finger touched the incriminating photograph.

"Francis," she said, "isn't there one thing, now, that must be between us?"

He came forward a pace or two. He stood at the desk looking down to where her accusing finger pointed. But when he raised his eyes they met hers steadily, without a trace of guilt.

"What?" he asked.

"You know—oh, you know!" Sylvia cried. "You think—you think I could ever love—could marry—the man who murdered my father?"

Seymour's expression did not change. "And if I risked that," he said, "it was for you. Yes. I killed your father... And I put my own life in forfeit. And I was ready to, if it meant that you married me."

Sylvia could only stare at him in horror. She suddenly felt that she was dealing with someone who was not quite sane. "Your father," he went on, "and her... I have put my neck twice into the noose. I suppose that I shall pay the penalty; that you will go to the police. And you—you were the cause of it all."

"No! No!" she cried out violently. "How could I be? How could I know? And why should you kill him—you? He was always kind to you—"

"That had nothing to do with it." There was the same unnatural calm about his voice. "I had no quarrel with Roseland. I killed him simply because he was an obstacle to our marriage; or would have been. He would have told you—"

"About—about the woman?" she said softly as he paused.

"About the woman... If you had loved me as I love you, you might have understood; I might have told you. But you did not. When you knew, it would have been the end of everything. It would?"

She did not answer his question. "But, don't you see, it was because I didn't love you—like that?... We couldn't have gone on... And now—now—"

"If you loved me as I love you." His voice was still quiet, but his eyes were burning. "Now, even now, you would love me—marry me! Even your father's body—"

She cried out, scarcely knowing what she did. Then his hand shot across the desk and gripped her wrist so that she could have fainted with the pain. He came round towards her slowly, and she felt herself drawn irresistibly towards him.

"No!" she pleaded. "No!"

Seymour's grip shifted. With both hands he seized her shoulders, staring into her eyes. Somehow the very pain of his clutch helped her to remain conscious.

"You think that he shall have you?" he asked. "Danton? You think I would let him? That you should go to the police—tell them about me? That I should die—alone? And leave you to him?"

Unexpectedly he released her. She staggered back, until the wall barred her further progress. She felt incapable of any movement, any effort to escape. His eyes seemed to pierce into her.

"Danton," he said with a dreadful quiet in his voice. "Danton. What has he done for you, risked for you, suffered for you? How does he love you?... I saw how it was. I saw, even this morning; even yesterday... And you think I will leave you for him?"

"If—if you loved me," she tried to appeal, "if you really loved me... you would want me to be happy."

"But I am not made like that." There was something like regret in his voice, but the madness in his eyes did not change. "I could not bear—I will not. That you should love him, that he should marry you, when I have failed... We shall go together. There shall be no courts, no flummery of trial and execution. I shall pay my penalty... But with you."

She wanted to scream; but she could not. She longed to dash past him; to try to reach the door; but she was incapable of moving. His eyes seemed to fascinate her. Slowly, unhurriedly, he felt in his breast pocket and produced a note-case. His fingers sought an inner compartment; but his eyes did not leave hers. She watched him helplessly. Then he tossed the case on to the desk, and in his fingers she saw a dark splinter of wood. But still she could not move.

"One prick," he said. "And then—what next? We shall find it—together..."

He was coming closer, and the tiny poison dart was in his hand. Instinctively she shrank back against the wall. Fear had left her. With the certainty of death upon her, she felt a strange resignation. He raised his hand.

"And now—good-bye. Sylvia—"

He whirled round as the door burst open. Danton stood there, and behind him were McCleod and the superintendent. For an instant no one moved. At a glance Danton took in the shrinking girl and the dark splinter in Seymour's hand. As Seymour turned purposefully he sprang across the room, gripping the demonstrator's wrist. They went to the ground together, and in the face near his own Danton saw the murderous intention. He felt his grip being broken. The big man would have been more than his match in any conditions, and now he had the strength of madness. A cruel smile showed on Seymour's face. With a jerk he released his wrist. And then McCleod seized him, dragging him away. His struggles ceased. He seemed suddenly to go limp.

"And, after all, I go—alone!" he said quite softly, and as he spoke his hand moved. The dart pierced his neck. A single spasm shook him; as if with a last effort, he turned his eyes to where the girl stood. Then he sank down limply, and his eyes closed.

"Sylvia! Sylvia!" Danton was on his feet, and his arms were about her. "You—you're not hurt? I came—in time?"

She shook her head. All at once she sobbed convulsively, clinging to him like a frightened child.

McCleod looked from them to the body on the ground. A grim smile showed on his face.

"And that's the end," he said. "Well, it's for the best... Carbis, our case is finished!"

---

CHAPTER XX
The Whole Story

THERE seemed to be almost a little crowd in the library when, in answer to an invitation by McCleod, Danton was ushered in by a bewildered parlourmaid that night. Smith, lying on the sofa, greeted him with a benignant smile. McCleod and Carbis stood by the fireplace, and in the background Sergeant Ambrose was making himself unobtrusive after his habit. Dr. Boynley, as host to his unusual guests, advanced to meet him.

"Sit down, Mr. Danton... I expect you are surprised by all this. I am myself! But, now that we hope it is settled—"

Danton allowed himself to be placed in a chair; he accepted a cigarette. The one fact which really dawned upon him was that the person he most wished to see was absent. He wondered where Sylvia Roseland was. Boynley, understanding what he felt, managed an aside.

"We thought, Mr. Danton, that my niece—was better away from this meeting. There is no occasion for her to be here—and you will understand, the strain..."

Danton nodded; and then McCleod was speaking.

"I expect you're surprised by all this, Mr. Danton," he said. "And I'm far from sure it's official. But as we paid you the doubtful compliment of thinking you were the murderer, and as you gave us a short cut at the end, I thought you'd like to know about it."

"I should," Danton said fervently. For the moment he could scarcely believe that the strain of the past thirty-six hours was over. But he felt an immense relief that McCleod once again treated him as an ordinary man, and not as a potential murderer. "I suppose it is all over?" he asked a little dubiously.

"Absolutely. The fact is, just at the time you had your inspiration about the tree, and Miss Roseland spotted the photograph, we were in a position to get Seymour. It might have taken us some time; but it would have been fairly certain." McCleod smiled. "I'm not saying all this as a defence. No doubt the police force has been grossly inefficient—and the amateurs, helped by luck, have beaten us to it... But, really, we didn't waste time, and we followed up things to the best of our ability."

Danton was in no mood to argue. He felt slightly elated by the removal of the strain; as long as he did not think of Seymour, but concentrated on an abstract murderer. The group round the fireplace was finding itself chairs, making itself comfortable for what was evidently a dénouement. He felt a vague distaste mingled with his curiosity. And, partly, that the whole thing was a waste of time. He wanted to see Sylvia Roseland.

"There's a good deal to explain," Carbis said thoughtfully, "and a lot I never understood! McCleod—"

"McCleod has done practically nothing," the inspector broke in. "If I can pride myself on anything it is that I know what has happened—now that it's over. I'll tell you."

Everyone was seated. McCleod took a long pull at his pipe, and expelled the smoke slowly before he began.

"The complication about Roseland's murder," he said, "was that the murderer had to change his mind twice; and that each time he left traces of the original plan. That accounts for the terribly muddled clues. Strictly speaking, there are clues for three murders; the one Seymour did; the one he first meant to do; and the one he tried to do the second time. In a way it made it more difficult to deal with; but, once it began to crack up, the very complications made proof easier."

He paused for a moment. "I think it's fairly clear what happened. About three years ago, Seymour had some kind of an affair with Alice Ridworth when she was in service in the town. Now, in a place like this, it's almost a miracle to keep anything like that dark; but Seymour brought it off. He took the most elaborate precautions; never met her in town; never wrote by post. When he wrote at all, it was in a disguised hand and the letters were left in the tree—"

"I do not wish to interrupt you, Inspector," Boynley broke in. "But perhaps I may say that Mr. Seymour was ambidextrous. In all probability he wrote with his left hand."

"I shouldn't be surprised. As a matter of fact, he did his job so well that I'm far from certain if the letters I found in London can be identified as written by him; and so well that, after I'd read them, I wasn't much wiser than before. Alice Ridworth herself didn't know either his real name or where he worked. And she doesn't seem to have known the name of the Juliot Research Institute. That puzzled me at first; but apparently the place is always known locally as the laboratory. I suppose that, though she lived here, she never troubled about the place. Well, she went away, and Seymour must have thanked Heaven he was rid of her. And so he might have been, but for the facts that she struck a bad time and that about a month ago a celebrated personage paid a visit here—"

"Of course!" Danton exclaimed. "Sorry."

"Well, a photograph was taken by the man on the local paper, and it included Roseland, Seymour and the other members of the Institute. And the local paper published it with the names in full. The national papers used it, too; but they gave only Roseland's name and the name of the Institute. Alice Ridworth recognised Seymour's face, and wrote to Roseland asking for the name. Now, Roseland seems to have scented trouble, and wanted to avoid any scandal. Instead of giving any names, he said that he would come and see her last week-end, when he went up to London for the conference. And, not thinking it was Seymour, he told Seymour, and Seymour saw that something would have to be done. To have the whole affair dragged out meant the end of his engagement to Sylvia Roseland. He didn't know the woman's address, so she was safe; but after thinking it over he decided to kill Roseland. And he seems to have thought that he would be all right then for a little while."

McCleod paused and frowned. "Mind you, a lot of this is speculation. As they're all dead, we can't know what they thought; but it must have been something like this. Personally, I don't think Seymour was quite in his right mind. The fact is that he was very much in love with Miss Roseland, and hoped to get the marriage over before the scandal could come up. Besides, once the danger of Roseland's visit was removed, it might not come up at all. So he laid his plans for the murder. Or rather, he laid his first plan."

"But I've never seen why he didn't try to get it accepted as natural death," Carbis objected. "With Roseland's heart like that—"

"The point is that he didn't know Roseland was ill that way. And I think he worked it out like this. 'I am a chemist, and I have access to all kinds of poisons. If poisons are used, I am bound to be one of a limited number of suspects. So, I will murder Roseland by knocking him on the head, in a way any ordinary person might choose.' I believe that was his original idea; though he spoilt it afterwards."

"And it was pretty sound," Carbis admitted. "But still, why let it look like murder? In fact, why make it look like murder?"

"Because he didn't know how easy Roseland would be to kill," McCleod explained patiently. "He'd expected to have to batter Roseland's head in. There wasn't any chance of its being accepted as natural death. And then, quite a light, clumsy blow does the business; but he goes on according to his original scheme. Now, if he'd been content to hit Roseland on the head and do nothing, we should have found it very difficult; though the second murder might have put us on the track. But he isn't content to leave the murderer unknown. He arranges for the police to have a perfectly good line of investigation to follow, and that's where Smith came in."

"Smith?" Danton said curiously. "I never quite understood—" He broke off as Smith laughed quietly.

"Why we let him off so lightly? Well, it's a point I'm not anxious to go into very much. But Smith had been a spy of sorts in the war, and that was how he met Roseland—and me—" He caught Carbis's grin, and smiled ruefully. "So, when he wrote to say he was coming, Roseland must have announced the visit, and have referred to Smith's spying, without making it clear on which side he had been. Seymour thought it was a golden opportunity. Through Couche and his curiosity, he starts to build up the legend of Roseland's having found a new poison gas and being threatened by enemy agents. He prepared the letters, not taking all that trouble about them, because he'd a small respect for Couche's intelligence, and he wasn't intending anyone else to see them. Afterwards, no doubt, he retrieved and burnt them. And then the first catch comes in. He wanted to know definitely whether Couche had seen the letters and would respond properly, and tries a few questions. Couche takes fright, and gives Seymour the impression that he hasn't seen them after all—"

"I remember," Danton said. "Couche said something to me about Seymour's having spoken to him about reading letters."

"Of course, he did it clumsily. But apparently there was no harm done. However, he abandoned that scheme, and thought of another. This was to take advantage of the fact that Roseland was unpopular with everyone at the laboratory, except himself. As it happened, it was even possible to include you, Dr. Boynley. I've no doubt that he actually engineered that conversation about war, knowing your strong views on the subject. So there were five people, not to mention Couche, who didn't feel very amiable to the Professor. He decided to leave evidence against all of them."

"A bit wholesale?" Carbis suggested. "Why not concentrate on one?"

"I think his difficulty was this. Suppose he had made all preparations, and planted clues pointing exclusively at, say, you, Mr. Danton. You might have gone off for the week-end, or otherwise established the fact that you couldn't have done it... If he laid clues against all of them, he was increasing the chances that someone wouldn't have an alibi. And, to make it complete, he included himself. It was a good move. As a matter of fact, we'd decided that he wouldn't do that."

"It was pretty risky," Carbis suggested.

"Not very. For one thing, he intended to have an alibi. For another, he chose to leave one of the poison darts—and he could prove that Roseland hadn't been killed by one. So it looked like a clumsy attempt to fix the killing on him. Also, it was intended to be the clue pointing to Danton—one of a rather more subtle type than the others. Because you, Mr. Danton, had had the chance to get that dart, and you might have left it there to put the blame on Seymour. As a matter of fact, it did make us suspect you."

"I know," Danton said grimly. "Though I helped things along a bit myself. You caught me every time at the wrong moment."

"That's how it happens... So far, Seymour had reasoned things out pretty well; but about now, I think, he got a little muddle-headed. He was hesitating between several ideas, and among others he seems to have got hold of the bracket scheme. Perhaps that was a final effort, intended to make it look like natural death; with, in reserve, the fact that, if it wasn't accepted as natural death, there were clues against the students and Dr. Boynley. I doubt if he ever thought that we should be so much worried about poison; but as it worked out, everything happened so quickly that it couldn't worry us. There was, incidentally, another reason why he staged that bracket trick. I'll come to that later. Anyway, by Friday evening he had got everything settled, including his alibi.

"That was perfectly simple. Seymour's friend Whitley was about the same build and wore the same hat and coat. He arranged for Whitley to motor down, and then borrowed his car, sending Whitley back by train, and promising to bring the car on himself. The thing none of us realised at first was that it wasn't Seymour the clerk and collector identified; it was a hat and coat like Seymour's. And he knew that he could get into the lantern lecture, say, half an hour late, and no one would be able to swear just when he arrived. There were several fine points about that business. Whitley had to be noticed; so he palmed off that dud note on him, so that the ticket collector would remember. And then, I gather, he asked Whitley to telephone for him, and said there was a telephone on the platform. There isn't; so Whitley had to pass the collector four times in all. It was pretty certain that the man in the funny coat would be remembered, but there was a risk. You must have given Seymour some nasty moments, Mr. Danton."

"I?" Danton asked. "Why, I proved the alibi for him!"

"Yes. But the risk was that they'd remember the man's face, and Whitley and Seymour weren't at all alike. If he'd let things die down a bit, that risk would be lessened. But it actually worked out all right... Now, on Friday night the course of events is roughly this. Seymour has got everything ready to have Roseland murdered in the laboratory, and he expects him to go there before he leaves for his train. But then, at the last moment, Roseland decides not to go. Seymour has to adjust his plans again. He gets the bracket, waylays Roseland in the garden, and kills him. Then he has to get the body into the laboratory; because most of the clues which he had planted won't look half so well outside, and he wants to keep it dark as long as possible. But he might meet someone. He hides the body and the weapon in the rockery for a time while he scouts round. The body made a small blood mark, and there was a chip of paint from the bracket. Finding that the coast is clear, he takes the body in, screws the bracket on and paints it; and then motors to town. And he believes everything has gone off all right. You see, he hopes he has an alibi. His motive is one he thinks no one can find out; and he hasn't done the murder the way he might be expected to do it. As a matter of fact, his position was quite strong. But there were weaknesses."

He paused for a moment. "Now, as it happened, the police weren't called upon to make any great effort in this business. Just when we were getting on to the right track, two things happen. The first is that Mr. Danton gets his inspiration about the tree—and that's where, in his haste, Seymour had made his one fatal mistake. The pencil impressions on that paper really connected him with the woman's death. And the second thing is that Miss Roseland, quite accidentally, sees the photograph of Whitley and himself together, and jumps to a conclusion. That was really hard luck. She might very well have seen it and passed it over; she mightn't have seen it at all... But the point I wanted to make was this. The weakness about his second scheme was that it pointed definitely to one of a limited number of people to whom the laboratory was accessible, and who could get and plant the clues. And the weakness about the last scheme, quite apart from the mistake in hitting with the wrong side of the bar, was that there were too many remnants of the previous schemes.

"Suppose Seymour had, from the beginning, decided to do that bracket trick and nothing else. It was his bad luck that the doctor was a little suspicious; but that might have been got over. I'm inclined to think the doctor wouldn't have made a fuss; he'd just have been as careful as possible in seeing that poison hadn't been used. But at this point the spy scheme, which he thinks has never worked at all, suddenly comes up. Smith is actually on the spot; Couche starts accusations of murder—against spies. But this murder really can't be done by spies, unless we assume that there's one among the students. His second scheme has spoilt the spy scheme. And Seymour knows, you see, that if it is ever investigated, there will be plenty of signs of murder; because he's arranged them himself. He decides his safest line is to be awfully active; and he really is anxious that no clues should be destroyed, because he knows that the clues are no good. And it works out very much as he had hoped. We start off by suspecting him; and then decide he's innocent. Thanks, partly, to Mr. Danton."

Danton frowned a little, not in annoyance, but at the thought of what Sylvia Roseland had gone through, and had still to go through. But McCleod misinterpreted it.

"We should have done the same ourselves," he said in apology, "so there's nothing to be ashamed of... But now the one thing Seymour hopes won't happen proceeds to happen. Alice Ridworth sees the account of Roseland's death and decides to come right down herself. And she doesn't warn Seymour. She can't warn him, because she still doesn't know his name. For it wasn't the name she got from her friend the process worker—oh, I suppose you don't know about that, but it doesn't matter—it was merely the fact that the photo came from the local paper, and that she might find out there. It's only after she arrives that she really thinks about this. That, Mr. Danton, is why she suddenly slowed down. The first shop she went into in High Street was the stationer's, which also prints the local rag. And she found what she wanted there, and rang up."

McCleod sighed, and relit his pipe. At this point I must plead guilty to carelessness. For though I put a man at the lodge to tap telephone calls, I didn't realise there was a private line to the house which didn't go through the lodge. She got through quite all right, and Seymour must have been almost bowled over. But he recovered pretty quickly. And then he did what was a really brilliant bit of planning, for the spur of the moment. She's got to be killed; but a second murder, and more particularly the murder of a woman which indicates the real motive, is going to narrow the field very much. The odds are that several people will have alibis; but he arranges a perfect one for himself. No one, he thinks, is going to be there when the woman dies. He plants the dart, and the sheet of paper as a bait in case she looks in; and he's told her that he'll leave a letter, or money, in the hollow tree that they used as their post-box."

"But this time the weapon was one traceable to him," Smith interjected.

"Yes. In a way, that is. I don't think he'd ever meant to use one of the darts to kill anyone, but he had no choice. And now he'd put over that story about Danton; and he knew Danton was suspect; and he'd been particularly helpful about the darts. He took the chance, and it really worked out all right. I think none of us really thought of him?"

He looked at Carbis. The superintendent shook his head.

"I didn't, anyway," he admitted. "But having Mr. Danton actually on the scene—not to mention Mr. Wiedermann and Dr. Boynley—was tremendous luck."

"Yes. Perhaps, too, we ought to have thought of some way in which the woman could be killed in the absence of the murderer. It's curious that that idea occurred to us in connection with Roseland's death—when we wondered if he'd been poisoned. But the second murder, through no fault of his, at least in the way he committed it, was bound to be fatal. Because one thing I did find out in London was that we had to look for something that happened three years back. And none of the students was here then. It practically left us with Seymour and Dr. Boynley—and, when I'd heard what Carbis had found, I should have known that Dr. Boynley couldn't have carried Roseland's dead body inside. So I was coming back with the intention of going over his alibi all over again; though I still didn't see the catch."

"But could you have proved anything?" Dr. Boynley asked.

"I think so. Because, for one thing, that alibi, if we tackled it properly, would not merely collapse; but in its collapse it would show that he had been lying. Of course, like anyone else in the laboratory, Seymour could have arranged everything that happened. Then, he was the one person who was indicated by the letters and who could have committed the murder of Roseland... Further investigation would be bound to show all kinds of small details confirming the charge against him; even apart from his confession to Miss Roseland, and, of course, his murderous attempt upon her... For example, we have already against him a piece of the broken glass found in his waste box. We should certainly have got him." He smiled grimly. "And a nice sensational case it would have made!"

"No doubt," Boynley agreed. "But, without wishing to rob you of your triumph, Inspector, I am very glad that it did not... My poor niece—"

Danton moved a little uneasily; but McCleod only shrugged his shoulders a little.

"Surely some trouble is better than that she should have married a murderer?" he said. "It was not only one murder he did, but two. He was ready to do others. Even your niece—"

"Yes, yes!" Boynley assented hastily. "No doubt you are right... But now, Inspector, I feel that my niece needs me... And, Mr. Danton, she was asking for you."

Danton said nothing, but he rose to his feet and followed Boynley towards the door, conscious that the others were eyeing him in some amusement. But he did not care. He followed Boynley out into the passage, and along it. Outside the drawing-room door the old man stopped.

"My niece was asking for you, Mr. Danton," he said. "She is in there... I do not doubt that you can comfort her in a way which I cannot. I am an old man. Soon she will be alone, unless—unless... But we won't think of that. There has been enough death here."

He smiled. Danton hesitated; then, impulsively, he seized the old man's hand and wrung it before he opened the door.

Sylvia was sitting in a chair by the fire; there was a book open on her knee, but she was not reading it. Only as she saw him her face brightened. She half rose to meet him, and the book slipped unheeded to the ground.

"I—well, McCleod thought I should like to hear all about it," he said. "I suppose that you—"

The expression on her face made him break off. There was silence for a moment.

"I don't want to hear about it—ever," she said at last, staring into the fire. "It is all ended. I hope that, in time, I shall be able to forget. To forget most things—"

"Most things?" Danton prompted, and though he knew that he ought to speak, something restrained him.

"Not all... To-day, when you risked your life to save me... To-day, on the hillside... If we could only be like that... If we could stay on the hillside..."

With a sudden courage which did not seem to be his own, Danton sank on his knees, and his arms went around her. For a moment he looked into her eyes.

"But we shall!" he said, and kissed her.

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THE END

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Roy Glashan's Library
Non sibi sed omnibus
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