They went up to the drawing-room and found the red-faced young policeman seated on a chair by the door eating a lunch, which had been sent up to him from the millionaire’s kitchen, with a very hearty appetite. They went into the drawing-room. Guerchard shut the door and turned the key: “Now,” he said, “I think that M. Formery will give me half an hour to myself. His cigar ought to last him at least half an hour. In that time I shall know what the burglars really did with their plunder—at least I shall know for certain how they got it out of the house.” “Please explain,” said the Duke. “I thought we knew how they got it out of the house.” And he waved his hand towards the window. “Oh, that!—that’s childish,” said Guerchard contemptuously. “Those are traces for an examining magistrate. The ladder, the table on the window-sill, they lead nowhere. The only people who came up that ladder were the two men who brought it from the scaffolding. You can see their footsteps. Nobody went down it at all. It was mere waste of time to bother with those traces.” “But the footprint under the book?” said the Duke. “Oh, that,” said Guerchard. “One of the burglars sat on the couch there, rubbed plaster on the sole of his boot, and set his foot down on the carpet. Then he dusted the rest of the plaster off his boot and put the book on the top of the footprint.” “Now, how do you know that?” said the astonished Duke. “It’s as plain as a pike-staff,” said Guerchard. “There must have been several burglars to move such pieces of furniture. If the soles of all of them had been covered with plaster, all the sweeping in the world would not have cleared the carpet of the tiny fragments of it. I’ve been over the carpet between the footprint and the window with a magnifying glass. There are no fragments of plaster on it. We dismiss the footprint. It is a mere blind, and a very fair blind too—for an examining magistrate.” “I understand,” said the Duke. “That narrows the problem, the quite simple problem, how was the furniture taken out of the room. It did not go through that window down the ladder. Again, it was not taken down the stairs, and out of the front door, or the back. If it had been, the concierge and his wife would have heard the noise. Besides that, it would have been carried down into a main street, in which there are people at all hours. Somebody would have been sure to tell a policeman that this house was being emptied. Moreover, the police were continually patrolling the main streets, and, quickly as a man like Lupin would do the job, he could not do it so quickly that a policeman would not have seen it. No; the furniture was not taken down the stairs or out of the front door. That narrows the problem still more. In fact, there is only one mode of egress left.” “The chimney!” cried the Duke.