ed 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?"

"Yes; I think you have disposed of that theory, sir," said the
inspector with ready acquiescence.

"All the same, I'd wager anything that we haven't disposed of it to the
satisfaction of Guerchard," said M. Formery.

"Then he must be very hard to satisfy," said the Duke.

"Oh, in any other matter he's open to reason," said M. Formery; "but
Lupin is his fixed idea; it's an obsession--almost a mania."

"But yet he never catches him," said the Duke.

"No; and he never will. His very obsession by Lupin hampers him. It
cramps his mind and hinders its working," said M. Formery.

He resumed his meditative pacing, stopped again, and said:

"But considering everything, espe