At last he seemed to come to some conclusion. He turned away from the window, drew a small magnifying-glass from his pocket, dropped on his hands and knees, and began to examine the surface of the carpet with the most minute care. He examined a space of it nearly six feet square, stopped, and gazed round the room. His eyes rested on the fireplace, which he could see under the bottom of the big tapestried fire-screen which was raised on legs about a foot high, fitted with big casters. His eyes filled with interest; without rising, he crawled quickly across the room, peeped round the edge of the screen and rose, smiling. He went on to the further drawing-room and made the same careful examination of it, again examining a part of the surface of the carpet with his magnifying-glass. He came back to the window to which the ladder had been raised and examined very carefully the broken shutter. He whistled softly to himself, lighted a cigarette, and leant against the side of the window. He looked out of it, with dull eyes which saw nothing, the while his mind worked upon the facts he had discovered. He had stood there plunged in reflection for perhaps ten minutes, when there came a sound of voices and footsteps on the stairs. He awoke from his absorption, seemed to prick his ears, then slipped a leg over the window-ledge, and disappeared from sight down the ladder. The door opened, and in came M. Formery, the Duke, and the inspector. M. Formery looked round the room with eyes which seemed to expect to meet a familiar sight, then walked to the other drawing-room and looked round that. He turned to the policeman, who had stepped inside the drawing-room, and said sharply, “M. Guerchard is not here.” “I left him here,” said the policeman. “He must have disappeared. He’s a wonder.” “Of course,” said M. Formery. “He has gone down the ladder to examine that house they’re building. He’s just following in our tracks and doing all over again the work we’ve already done. He might have saved himself the trouble. We could have told him all he wants to know. But there! He very likely would not be satisfied till he had seen everything for himself.” “He may see something which we have missed,” said the Duke. M. Formery frowned, and said sharply “That’s hardly likely. I don’t think that your Grace realizes to what a perfection constant practice brings one’s power of observation. The inspector and I will cheerfully eat anything we’ve missed—won’t we, inspector?” And he laughed heartily at his joke. “It might always prove a large mouthful,” said the Duke with an ironical smile. M. Formery assumed his air of profound reflection, and walked a few steps up and down the room, frowning: “The more I think about it,” he said, “the clearer it grows that we have disposed of the Lupin theory. This is the work of far less expert rogues than Lupin. What do you think, inspector?”