A minute more and Cleek was in the house—in the presence of Hammond and Petrie—and Narkom had introduced him as "Monsieur Georges de Lesparre, a distinguished French criminologist who had come over to England this morning upon a matter connected with the French Police Department and who, in the absence of Mr. Cleek, had consented to take up this peculiar case."

"My hat! Wouldn't that drive you to drink!" commented Petrie in a disgusted aside as he eyed this suave and sallow gentleman with open disapproval. "What will we be importing from the continent next, Hammond? As if there aren't detectives in England good enough to do the Yard's work without setting them to twiddling their blessed thumbs whilst a blooming Froggie runs the show and—beg pardon! what's that? Yes, Mr. Narkom. Searched the house from top to bottom, sir. Nobody in it, and nobody been here either, sir, not a soul since you left."

"You are quite sure, monsieur?" This from Cleek. "About the 'nobody in the house,' I mean, of course. You are quite sure?"

"Of course we're sure!" snapped Hammond savagely. "Been from the top to the bottom of it—me and Petrie and the constable here—and not a soul in it anywhere."

"Ah, the constable, eh? You shall tell me, please, Mr. Narkom, is this the constable who was at the one end of the arch while the keeper was chasing the man in at the other? Ah, it is, eh? Well—er—shall not we see the keeper, too? I do not find him about and I should much like to speak with him. Where is he?"

"Who—the keeper?" said Narkom. "Blest if I know. Is he about, my lads?"

"No, sir. Ain't been about—has he, Petrie?—for the Lord knows how long. Never thought of the beggar until this moment, sir."

"Nor did I," said Narkom. "Come to think of it, I haven't seen the fellow since we came to the 'Y' of the road and found those footprints leading here. No doubt he has gone back to his shelter on the Common and—— Monsieur! Why are you smiling? Good God! you— I—— Monsieur, shall I send my men for the fellow? Do you want to see him?"

"Yes, Monsieur Narkom, I want to see him very, very much indeed—if you can find him! But you can't, monsieur; and I fear me that you never will. What you will find, however, if you will send your men to the shelter of which you speak will be the real keeper, either dead or stunned or gagged, and his coat and hat and badge removed from his body by the man who personated him."

"Good heavens above, man, you don't mean to say——"

"That you had the real criminal in your hands and let him go, that you talked with him, walked with him, were taken in by him, and that he told you no lie when he said the assassin really did run into the arch," replied Cleek quietly. "It is the old old trick of that fellow who was called the 'Vanishing Cracksman,' my friend: to knock down the fellow who first gives the alarm, rip off his clothing, and then to lead the hue and cry until there's a chance to steal away unobserved. Send your men to the keeper's shelter and see if I have guessed the truth of that little riddle or not. I'll lay you a sovereign, my friend, that your man has slipped the leash, and it will be but a fluke of fate if you ever lay hands on him again."

In a sort of panic Narkom turned to his men and sent them flying from the house to investigate this startling assertion; and, turning as they went, Cleek walked into the room where that awful dead figure hung. He had taken but one step across the threshold, however, when he stopped suddenly and began to sniff the air—less to the surprise of Narkom, who had often seen him do this sort of thing before, than to Constable Mellish, who stood looking at him in open-mouthed amazement.

"Good lud, man— I should say, monsieur," exclaimed the superintendent agitatedly, "after what you have just hinted, my head is in a whirl and I am prepared for almost anything; but surely you cannot find anything suspicious in the mere atmosphere of the place?"

"No; nothing but what you yourself must have observed. There is a distinct odour of violets in the room; so that unless that unhappy man yonder was of the kind that scents itself, we may set it down that a woman has been in here."

"A woman? But no woman could do a thing like that," pointing to the position of the dead man. "Nor," after sniffing the air repeatedly, "do I notice anything of the odour which you speak."

"Nor me nuther, sir," put in the constable.

"Still, the odour is here," returned Cleek. "And—no! it does not emanate from the dead man. There is scent on him to be sure, but it is not the scent of violets. Odours last at best but a little time after the person bearing them has left the room, and as it must now be upward of an hour since the discovery of the crime——"

Cleek sucked in his upper lip and took his chin between his thumb and forefinger and pinched it hard. What was that that Narkom had told him regarding Lennard's startling experience after he had been left on guard at the old railway arch? Hum-m-m! Certainly there was one woman abroad in this neighbourhood to-night, and a woman decidedly not of the lower classes at that, as witness the fact that she had worn an ermine cloak. Certainly, that would point to the wearer being a woman to whom money was no object—and to Lady Katharine Fordham, with all the great St. Ulmer wealth behind her, it assuredly was not. Clearly, then, whoever was or was not the actual perpetrator of this night's crime, a woman of the higher walk of life—a rich and fashionable woman, in fact—was in some way connected with it.

The question was, did Lady Katharine Fordham possess an ermine cloak? And if she did, would she be likely to have brought it up from Suffolk at this time of the year? The curious smile slid down his cheek and vanished. He turned to Mr. Narkom, who had been watching him anxiously all the time.

"Well, my friend, let us poke about a bit more till your assistants get back from the shelter on the Common," he said and dropped down on his knees, examining every inch of the flooring with the aid of a pocket torch and a magnifying glass. For some moments nothing came of this, but of a sudden Narkom saw him come to an abrupt halt.

Twitching back his head, he sniffed at the air, two or three times, after the manner of a hound catching up a lost scent; then he bent over, brought his nose close to the level of the bare and dirty boards, sniffed again, blew aside the dust, and exposed to view a tiny grease spot not bigger than a child's thumbnail.

"Huile Violette!" he said, with a sound as of satisfied laughter in his voice. "No wonder the scent of violets lingered. Look! here is another spot—and here another," he added, blowing the dust away and creeping on all fours in the direction the perfumed trail led. "Oh, I know this stuff well, my friend," he went on. "For many, many years its manufacture was a secret known only to the Spanish monks who carried it with them to South America and subsequently established in that part of the country now known as Argentina a monastery celebrated all over the world as the only source from which this essential oil could be procured."

"Argentina?" repeated Narkom agitatedly. "My dear chap, have you forgotten that it was in Argentina Lord St. Ulmer spent those many years of his self-imposed exile? If then, the stuff is only to be procured there——"

"Gently, gently—you rush at top speed, Mr. Narkom. I said 'was,' recollect. It is still the chief point of its manufacture, but since those days when the Spanish monks carried it there others have learned the secret of it, notably the Turks who now manufacture an attar of violets just as they have for years manufactured an attar of roses. It is enormously expensive; for the veriest drop of it is sufficient, with the necessary addition of alcohol, to manufacture half a pint of the perfume known to commerce as 'Extract of Violet.' At one time it was a favourite trick of very great ladies to wear on a bracelet a tiny golden capsule containing two or three drops of it and supplied with a minute jewelled stopper attached to a slender golden chain, which stopper they occasionally removed for a moment or two that the aroma of the contents might diffuse itself about them. I knew one woman—and one only—who possessed such a bracelet. You, too, have heard of her. Whatever her real name may be, she is simply known to those with whom she associates as 'Margot.'"

"Scotland! The queen of the Apaches?"

"Yes."

"You are sure of that?"

"I ought to be. I, myself, stole the bracelet from the collection of the Comte de Champdoce and presented it to her. I remember that the stopper to the capsule was carved from a single emerald that, owing to its age—it was said to have belonged in its day to Catherine de Medicis—had worn loose, and could only be prevented from dropping out and allowing the contents to drip away by wedging it into the orifice in the capsule by winding the stopper with silk."

Narkom's face positively glowed.

"My dear Cleek, you give me the brightest kind of hope," he said enthusiastically, as he stooped and investigated the tiny, perfumed grease spots on the floor, so clearly made by the dropping of some oily substance that there could be no question regarding their origin. "Then, there can be no possibility of connecting young Geoff Clavering or the girl he loves with this ghastly business if that Margot woman has been here, and it was from her bracelet that these stains were dropped? Besides, after what you said about that fellow of her crew who was spiked to the wall as this poor wretch here is——"

"A moment, my friend—you are on the rush again," interjected Cleek. "All that we actually know, at present, Mr. Narkom, is that some one, and very likely a woman, has been here and—unconsciously, of course—has spilled some drops of a very valuable and highly concentrated perfume. This naturally points to a defective stopper to the article containing that perfume, but whether or not that defective stopper was one carved from a single emerald and wound with silk——"

He stopped and let the rest of the sentence go by default. All the while he had been speaking he had been following, after the manner of a hound on the scent, the trail of that perfume's lead; now it had brought him to a litter of rat-gnawed paper and a parcel containing a peach and the remnants of a roasted fowl. As if the scent seemed stronger here than elsewhere—so strong, in fact, that it was suggestive of a goal—he began tossing the scraps about, till at last he gave a sort of cry and pounced upon something in a distant corner.

"Cleek!" rapped out Narkom in an excited but guarded tone, as he noted this, "Cleek, you have found something? Something that decides?"

"Yes," the detective made answer. "Something which proves that, whoever the woman who dropped the scent may be, Mr. Narkom, she was not Margot!"

He unclosed his hand and stretched it out toward the superintendent, and Narkom saw lying on his palm a crushed and gleaming thing which looked like a child's gold thimble that had been trodden upon. The snapped fragment of a hairlike gold chain still clung to it, and at the end of this dangled a liliputian stopper, a wee mite of a thing that was little more than a short, thick pin of plain, unjewelled, unornamented gold.

"One of the 'capsules' of which I spoke, you see," said Cleek, "and bearing not the slightest resemblance to the one belonging to Margot. The thing has snapped from its fastening and been trodden upon—trodden under a very heavy foot, I should say, from the condition of it. There is something engraved upon it, something that won't tend to ease your mind, Mr. Narkom. Take my glass and look at it."

Narkom did so. Engraved on the crushed and fragrant-smelling bit of gold he saw a coat-of-arms—arms which he, at least, knew to be those of the house of St. Ulmer—and under this the name "Katharine."

"Good Lord!" he said, and let the crushed bauble fall back upon the palm from which he had lifted it. "That child—that dear girl who is as much as life itself to young Geoff Clavering? But how could she—a slip of a girl like that——"

He turned and looked over at the dead figure spiked to the cottage wall.

Cleek made no reply—at least for the moment. He had gone back to the "hound's trick" of sniffing the trail and was creeping on again—past the litter of papers this time—and crawling on all fours toward the very doorway by which the police had first gained access to the room.

"Wait! Cross no bridges until you come to them," he said at last in an excited whisper. "Some one who trod upon that thing passed out this way. I knew I smelt the oil the very instant I crossed the threshold; now I can understand why. The assassin left by the very door you entered, but whether man or woman——"

By now the trail had led him to the very threshold of the room. Beyond lay the dark hall by which Narkom and his men had entered the house, and the light of his upraised electric torch shining out into that black passage showed him something that made his pulses leap. It was simply a fragment of some soft pinkish material, caught and torn off from a woman's skirt by a nail head that protruded above the level of the boarded floor. He rose and ran out to it; he caught it up and examined it; then, with a laugh, shut his hand over it and went hurriedly back to the superintendent's side.

"Mr. Narkom," he said, "tell me something! We have, presumably, found a perfume receptacle belonging to the Lady Katharine Fordham; but did you notice—can you remember what manner of frock her ladyship wore at Clavering Close to-night?"

"I remember it very well indeed. It was a simple white satin frock, very plain and very girlish, and she wore a bunch of purple pansies with it."

"Ah-h-h!" Cleek's voice was full of relief, his eyes full of sparkle and life. "Then she did not wear a gown of some soft, gauzy pink material, eh? An airy sort of gown trimmed at the hem with scalloped embroidery of rose-coloured silk. Good! Can you remember any lady to-night that did?"

"Yes," said Narkom promptly. "Miss Ailsa Lorne did. She wore some soft, gauzy pink stuff—chiffon, I think I've heard the wife call it—with a lot of rose-coloured silk stitchery on the edges of the flounces, and she had a band of pink ribbon in her hair."

Cleek made no comment, nor did his countenance betray even the slightest trace of emotion. He simply put the shut hand that held that gauzy pink fragment into his pocket and shoved it far down out of sight.

A while ago he could have sworn that Ailsa Lorne's foot had never crossed the threshold of this house of crime; now he knew that it had, and if the evidence of this scrap of chiffon stood for anything, crossed it after she had left Clavering Close—after she had heard that threat against the Count de Louvisan's life.