It was three o'clock when Juve arrived at the rue LÉvert, and he found the concierge of number 147 just finishing her coffee.

Amazed at the results achieved by the detective, the details of which she had learned from the sensational articles in the daily paper she most affected, Mme. Doulenques had conceived a most respectful admiration for the Inspector of the Criminal Investigation Department.

"That man," she constantly declared to Madame Aurore, "it isn't eyes he has in his head, it's telescopes, magnifying glasses! He sees everything in a minute—even when it isn't there!"

She gave him an admiring "good afternoon, Inspector," as he came into her lodge, and going to a board on which numbers of keys were hanging, took one down and handed it to him.

"So there's something fresh to-day?" she said. "I've just seen in the paper that M. Gurn has been arrested. So it was my lodger who did it? What a dreadful man! Whoever would have thought it? It turns my blood cold to think of him!"

Juve was never a man for general conversation, and he was still less interested in the garrulity of this loquacious creature. He took the key and cut short her remarks by walking to the door.

"Yes, Gurn has been arrested," he said shortly; "but he has made no confession, so nothing is known for certain yet. Please go on with your work exactly as though I were not in the house, Mme. Doulenques."

It was his usual phrase, and a constant disappointment to the concierge, who would have asked nothing better than to go upstairs with the detective and watch him at his wonderful work.

Juve went up the five floors to the flat formerly occupied by Gurn, reflecting somewhat moodily. Of course Gurn's arrest was a success, and it was satisfactory to have the scoundrel under lock and key, but in point of fact Juve had learned nothing new in consequence of the arrest, and he was obsessed with the idea that this murder of Lord Beltham was an altogether exceptional crime. He did not yet know why Gurn had killed Lord Beltham, and he did not even know exactly who Gurn himself was; all he could declare was that the murder had been planned and carried out with marvellous audacity and skill, and that was not enough.

Juve let himself into the flat and closed the door carefully behind him. The rooms were in disorder, the result of the searches effected by the police. The rent had not been paid for some time, and as no friend or relation had come forward to assume control of Gurn's interests, the furniture and ornaments of the little flat were to be sold by auction.

The detective walked through the rooms, then flung himself into an arm-chair. He did not know precisely why he had come. He had searched the place a dozen times already since his discovery of the corpse within the trunk, and had found nothing more, no tell-tale marks or fresh detail, to assist in the elucidation of the mystery. He would have given very much to be able to identify Gurn with some other of the many criminals who had passed through his hands, and still more to be able to identify him with that one most mysterious criminal whose fearful deeds had shocked the world so greatly. Somehow the particular way in which this murder was committed, the very audacity of it, led him to think, to "sense," almost to swear that——

Juve got up. It was little in accord with his active temperament to sit still. Once more he went all round the flat.

"The kitchen? Let me see: I have been through everything? The stove? The cupboards? The saucepans? Why, I went so far as to make sure that there was no poison in them, though it seemed a wild idea. The anteroom? Nothing there: the umbrella stand was empty, and the one interesting thing I did see, the torn curtain, has been described and photographed officially." He went back into the dining-room. "I've searched all the furniture: and I went through all the parcels Gurn had done up before he left, and would, no doubt, have come back for at his leisure, had it not been for my discovery of the body, and the unfortunate publicity the newspapers gave to that fact." In one corner of the room was a heap of old newspapers, crumpled and torn, and thrown down in disorder. Juve kicked them aside. "I've looked through all that, even read the agony columns, but there was nothing there." He went into the bedroom and contemplated the bed, that the concierge had stripped, the chairs set one on top of another in a corner, and the wardrobe that stood empty, its former contents scattered on the floor by the police during their search. There, too, nothing was to be found.

Against the wall, near the fireplace, was a little escritoire with a cupboard above it, containing a few battered books.

"My men have been all through that," Juve muttered; "it's most unlikely that they missed anything, but perhaps I had better see."

He sat down before it and began methodically to sort the scattered papers; with quick, trained glance he scanned each document, putting one after another aside with a grimace expressive of disappointment. Almost the last document he picked up was a long sheet of parchment, and as he unfolded it an exclamation escaped his lips. It was an official notice of Gurn's promotion to the rank of sergeant when fighting under Lord Beltham in the South African War. Juve read it through—he knew English well—and laid it down with a gesture of discouragement.

"It is extraordinary," he muttered. "That seems to be perfectly authentic; it is authentic, and it proves that this fellow was a decent fellow and a brave soldier once; that is a fine record of service." He drummed his fingers on the desk and spoke aloud. "Is Gurn really Gurn, then, and have I been mistaken from start to finish in the little romance I have been weaving round him? How am I to find the key to the mystery? How am I to prove the truth of what I feel to be so very close to me, but which eludes me every time, just as I seem to be about to grasp it?"

He went on with his search, and then, looking at the bookcase, took the volumes out and, holding each by its two covers, shook it to make sure that no papers were hidden among the leaves. But all in vain. He did the same with a large railway time-table and several shipping calendars.

"The odd thing is," he thought, "that all these time-tables go to prove that Gurn really was the commercial traveller he professed to be. It's exactly things such as these one would expect to find in the possession of a man who travelled much, and always had to be referring to the dates of sailing to distant parts of the world."

In the bookcase was a box, made to represent a bound book, and containing a collection of ordnance maps. Juve took them out to make sure that no loose papers were included among them, and one by one unfolded every map.

Then a sharp exclamation burst from his lips.

"Good Lord! Now there——"

In his surprise he sprang up so abruptly that he pushed back his chair, and overturned it. His excitement was so great that his hands were shaking as he carefully spread out upon the desk one of the ordnance maps he had taken from the case.

"It's the map of the centre district all right: the map which shows Cahors, and Brives, and Saint-Jaury and—Beaulieu! And the missing piece—it is the missing piece that would give that precise district!"

Juve stared at the map with hypnotised gaze; for a piece had been cut out of it, cut out with a penknife neatly and carefully, and that piece must have shown the exact district where the chÂteau stood which had been occupied by the Marquise de Langrune.

"Oh, if I could only prove it: prove that the piece missing from this map, this map belonging to Gurn, is really and truly the piece I found near VerriÈres Station just after the murder of the Marquise de Langrune—what a triumph that would be! What a damning proof! What astounding consequences this discovery of mine might have!"

Juve made a careful note of the number of the map, quickly and nervously, folded it up again, and prepared to leave the flat.

He had made but a step or two towards the door when a sharp ring at the bell made him jump.

"The deuce!" he exclaimed softly; "who can be coming to ring Gurn up when everybody in Paris knows he has been arrested?" and he felt mechanically in his pocket to make sure that his revolver was there. Then he smiled. "What a fool I am! Of course it is only Mme. Doulenques, wondering why I am staying here so long."

He strode to the door, flung it wide open, and then recoiled in astonishment.

"You?" he exclaimed, surveying the caller from top to toe. "You? Charles Rambert! Or, I should say, JÉrÔme Fandor! Now what the deuce does this mean?"