curtains hung before its door. He drew the curtains, and tried the handle of the door of the safe. It did not turn; the safe was locked.
"As far as I can see, they haven't touched this," said M. Formery.
"Thank goodness for that," said the Duke. "I believe, or at least my fiancee does, that M. Gournay-Martin keeps the most precious thing in his collection in that safe—the coronet."
"What! the famous coronet of the Princesse de Lamballe?" said M. Formery.
"Yes," said the Duke.
"But according to your report, inspector, the letter signed 'Lupin' announced that he was going to steal the coronet also."
"It did—in so many words," said the Duke.
"Well, here is a further proof that we're not dealing with Lupin. That rascal would certainly have put his threat into execution, M. Formery," said the inspector.
"Who's in charge of the house?" said M. Formery.
"The concierge, his wife, and a housekeeper—a woman named Victoire," said the inspector.
"I'll see to the concierge and his wife presently. I've sent one of your men round for their dossier. When I get it I'll question them. You found them gagged and bound in their bedroom?"
"Yes, M. Formery; and always this imitation of Lupin—a yellow gag, blue cords, and the motto, 'I take, therefore I am,' on a scrap of cardboard—his usual bag of tricks."
"Then once again they're going to touch us up in the papers. It's any odds on it," said M. Formery gloomily. "Where's the housekeeper? I should like to see her."
"The fact is, we don't know where she is," said the inspector.
"You don't know where she is?" said M. Formery.
"We can't find her anywhere," said the inspector.
"That's excellent, excellent. We've found the accomplice," said M. Formery with lively delight; and he rubbed his hands together. "At least, we haven't found her, but we know her."
"I don't think that's the case," said the Duke. "At least, my future father-in-law and my fiancee had both of them the greatest confidence in her. Yesterday she telephoned to us at the Chateau de Charmerace. All the jewels were left in her charge, and the wedding presents as they were sent in."
"And these jewels and wedding presents—have they been stolen too?" said M. Formery.
"They don't seem to have been touched," said the Duke, "though of course we can't tell till M. Gournay-Martin arrives. As far as I can see, the burglars have only touched these two drawing-rooms."
"That's very annoying," said M. Formery.
"I don't find it so," said the Duke, smiling.
"I was looking at it from the professional point of view," said M. Formery. He turned to the inspector and added, "You can't have searched thoroughly. This housekeeper must be somewhere about—if she's really trustworthy. Have you looked in every room in the house?"
"In every room—under every bed—in every corner and every cupboard," said the inspector.
"Bother!" said M. Formery. "Are there no scraps of torn clothes, no blood-stains, no traces of murder, nothing of interest?"
"Nothing!" said the inspector.
"But this is very regrettable," said M. Formery. "Where did she sleep? Was her bed unmade?"
"Her room is at the top of the house," said the inspector. "The bed had been slept in, but she does not appear to have taken away any of her clothes."
"Extraordinary! This is beginning to look a very complicated business," said M. Formery gravely.
"Perhaps Guerchard will be able to throw a little more light on it," said the Duke.
M. Formery frowned and said, "Yes, yes. Guerchard is a good assistant in a business like this. A little visionary, a little fanciful—wrong-headed, in fact; but, after all, he IS Guerchard. Only, since Lupin is his bugbear, he's bound to find some means of muddling us up with that wretched animal. You're going to see Lupin mixed up with all this to a dead certainty, your Grace."
The Duke looked at the signatures on the wall. "It seems to me that he is pretty well mixed up with it already," he said quietly.
"Believe me, your Grace, in a criminal affair it is, above all things, necessary to distrust appearances. I am growing more and more confident that some ordinary burglars have committed this crime and are trying to put us off the scent by diverting our attention to Lupin."
The Duke stooped down carelessly and picked up a book which had fallen from a table.
"Excuse me, but please—please—do not touch anything," said M. Formery quickly.
"Why, this is odd," said the Duke, staring at the floor.
"What is odd?" said M. Formery.
"Well, this book looks as if it had been knocked off the table by one of the burglars. And look here; here's a footprint under it—a footprint on the carpet," said the Duke.
M. Formery and the inspector came quickly to the spot. There, where the book had fallen, plainly imprinted on the carpet, was a white footprint. M. Formery and the inspector stared at it.
"It looks like plaster. How did plaster get here?" said M. Formery, frowning at it.
"Well, suppose the robbers came from the garden," said the Duke.
"Of course they came from the garden, your Grace. Where else should they come from?" said M. Formery, with a touch of impatience in his tone.
"Well, at the end of the garden they're building a house," said the Duke.
"Of course, of course," said M. Formery, taking him up quickly. "The burglars came here with their boots covered with plaster. They've swept away all the other marks of their feet from the carpet; but whoever did the sweeping was too slack to lift up that book and sweep under it. This footprint, however, is not of great importance, though it is corroborative of all the other evidence we have that they came and went by the garden. There's the ladder, and that table half out of the window. Still, this footprint may turn out useful, after all. You had better take the measurements of it, inspector. Here's a foot-rule for you. I make a point of carrying this foot-rule about with me, your Grace. You would be surprised to learn how often it has come in useful."
He took a little ivory foot-rule from his waist-coat pocket, and gave it to the inspector, who fell on his knees and measured the footprint with the greatest care.
"I must take a careful look at that house they're building. I shall find a good many traces there, to a dead certainty," said M. Formery.
The inspector entered the measurements of the footprint in his note-book. There came the sound of a knocking at the front door.
"I shall find footprints of exactly the same dimensions as this one at the foot of some heap of plaster beside that house," said M. Formery; with an air of profound conviction, pointing through the window to the house building beyond the garden.
A policeman opened the door of the drawing-room and saluted.
"If you please, sir, the servants have arrived from Charmerace," he said.
"Let them wait in the kitchen and the servants' offices," said M. Formery. He stood silent, buried in profound meditation, for a couple of minutes. Then he turned to the Duke and said, "What was that you said about a theft of motor-cars at Charmerace?"
"When he received the letter from Arsene Lupin, M. Gournay-Martin decided to start for Paris at once," said the Duke. "But when we sent for the cars we found that they had just been stolen. M. Gournay-Martin's chauffeur and another servant were in the garage gagged and bound. Only an old car, a hundred horse-power Mercrac, was left. I drove it to Paris, leaving M. Gournay-Martin and his family to come on by train."
"Very important—very important indeed," said M. Formery. He thought for a moment,