"One of M. Formery's innocents," said Guerchard, turning to the Duke.  
"The chalk?" said the Duke. "Is it the same chalk?"
 
"It's blue," said Guerchard, holding it out. "The same as that of the signatures on the walls. Add that fact to the woman's sudden realization of what she was doing, and you'll see that they were written with it."
 
"It is rather a surprise," said the Duke. "To look at her you would think that she was the most honest woman in the world."
 
"Ah, you don't know Lupin, your Grace," said Guerchard. "He can do anything with women; and they'll do anything for him. And, what's more, as far as I can see, it doesn't make a scrap of difference whether they're honest or not. The fair-haired lady I was telling you about was probably an honest woman; Ganimard is sure of it. We should have found out long ago who she was if she had been a wrong 'un. And Ganimard also swears that when he arrested Lupin on board the Provence some woman, some ordinary, honest woman among the passengers, carried away Lady Garland's jewels, which he had stolen and was bringing to America, and along with them a matter of eight hundred pounds which he had stolen from a fellow-passenger on the voyage."
 
"That power of fascination which some men exercise on women is one of those mysteries which science should investigate before it does anything else," said the Duke, in a reflective tone. "Now I come to think of it, I had much better have spent my time on that investigation than on that tedious journey to the South Pole. All the same, I'm deucedly sorry for that woman, Victoire. She looks such a good soul."
 
Guerchard shrugged his shoulders: "The prisons are full of good souls," he said, with cynical wisdom born of experience. "They get caught so much more often than the bad."
 
"It seems rather mean of Lupin to make use of women like this, and get them into trouble," said the Duke.
 
"But he doesn't," said Guerchard quickly. "At least he hasn't up to now. This Victoire is the first we've caught. I look on it as a good omen."
 
He walked across the room, picked up his cloak, and took a card-case from the inner pocket of it. "If you don't mind, your Grace, I want you to show this permit to my men who are keeping the door, whenever you go out of the house. It's just a formality; but I attach considerable importance to it, for I really ought not to make exceptions in favour of any one. I have two men at the door, and they have orders to let nobody out without my written permission. Of course M. Gournay-Martin's guests are different. Bonavent has orders to pass them out. And, if your Grace doesn't mind, it will help me. If you carry a permit, no one else will dream of complaining of having to do so."
 
"Oh, I don't mind, if it's of any help to you," said the Duke cheerfully.
 
"Thank you," said Guerchard. And he wrote on his card and handed it to the Duke.
 
The Duke took it and looked at it. On it was written:
 
"Pass the Duke of Charmerace."
"J. GUERCHARD."
 
"It's quite military," said the Duke, putting the card into his waistcoat pocket.
 
There came a knock at the door, and a tall, thin, bearded man came into the room.
 
"Ah, Dieusy! At last! What news?" cried Guerchard.
 
Dieusy saluted: "I've learnt that a motor-van was waiting outside the next house—in the side street," he said.
 
"At what time?" said Guerchard.
 
"Between four and five in the morning," said Dieusy.
 
"Who saw it?" said Guerchard.
 
"A scavenger. He thinks that it was nearly five o'clock when the van drove off."
 
"Between four and five—nearly five. Then they filled up the opening before they loaded the van. I thought they would," said Guerchard, thoughtfully. "Anything else?"
 
"A few minutes after the van had gone a man in motoring dress came out of the house," said Dieusy.
 
"In motoring dress?" said Guerchard quickly.
 
"Yes. And a little way from the house he threw away his cigarette. The scavenger thought the whole business a little queer, and he picked up the cigarette and kept it. Here it is."
 
He handed it to Guerchard, whose eyes scanned it carelessly and then glued themselves to it.
 
"A gold-tipped cigarette ... marked Mercedes ... Why, your Grace, this is one of your cigarettes!"
 
"But this is incredible!" cried the Duke.
 
"Not at all," said Guerchard. "It's merely another link in the chain. I've no doubt you have some of these cigarettes at Charmerace."
 
"Oh, yes, I've had a box on most of the tables," said the Duke.
 
"Well, there you are," said Guerchard.
 
"Oh, I see what you're driving at," said the Duke. "You mean that one of the Charolais must have taken a box."
 
"Well, we know that they'd hardly stick at a box of cigarettes," said Guerchard.
 
"Yes ... but I thought ..." said the Duke; and he paused.
 
"You thought what?" said Guerchard.
 
"Then Lupin ... since it was Lupin who managed the business last night—since you found those salvias in the house next door ... then Lupin came from Charmerace."
 
"Evidently," said Guerchard.
 
"And Lupin is one of the Charolais."
 
"Oh, that's another matter," said Guerchard.
 
"But it's certain, absolutely certain," said the Duke. "We have the connecting links ... the salvias ... this cigarette."
 
"It looks very like it. You're pretty quick on a scent, I must say," said Guerchard. "What a detective you would have made! Only ... nothing is certain."
 
"But it IS. Whatever more do you want? Was he at Charmerace yesterday, or was he not? Did he, or did he not, arrange the theft of the motor-cars?"
 
"Certainly he did. But he himself might have remained in the background all the while," said Guerchard.
 
"In what shape? ... Under what mask? ... By Jove, I should like to see this fellow!" said the Duke.
 
"We shall see him to-night," said Guerchard.
 
"To-night?" said the Duke.
 
"Of course we shall; for he will come to steal the coronet between a quarter to twelve and midnight," said Guerchard.
 
"Never!" said the Duke. "You don't really believe that he'll have the cheek to attempt such a mad act?"
 
"Ah, you don't know this man, your Grace ... his extraordinary mixture of coolness and audacity. It's the danger that attracts him. He throws himself into the fire, and he doesn't get burnt. For the last ten years I've been saying to myself, 'Here we are: this time I've got him! ... At last I'm going to nab him.' But I've said that day after day," said Guerchard; and he paused.
 
"Well?" said the Duke.
 
"Well, the days pass; and I never nab him. Oh, he is thick, I tell you.... He's a joker, he is ... a regular artist"—he ground his teeth—"The damned thief!"
 
The Duke looked at him, and said slowly, "Then you think that to-night Lupin—"
 
"You've followed the scent with me, your Grace," Guerchard interrupted quickly and vehemently. "We've picked up each clue together. You've almost seen this man at work.... You've understood him. Isn't a man like this, I ask you, capable of anything?"
 
"He is," said the Duke, with conviction.
 
"Well, then," said Guerchard.
 
"Perhaps you're right," said the Duke.
 
Guerchard turned to Dieusy and said, in a quieter voice, "And when the scavenger had picked up the cigarette, did he follow the motorist?"
 
"Yes, he followed him for about a hundred yards. He went down into Sureau Street, and turned westwards. Then a motor-car came along; he got into it, and went off."
 
"What kind of a motor-car?" said Guerchard.
 
"A big car, and dark red in colour," said Dieusy.
 
"The Limousine!" cried the Duke.
 
"That's all I've got so far, sir," said Dieusy.
 
"Well, off you go," said Guerchard. "Now that you've got started, you'll probably get something else before very long."
 
Dieusy saluted and went.
 
"Things are beginning to move," said Guerchard cheerfully. "First Victoire, and now this motor-van."
 
"They are indeed," said the Duke.
 
"After all, it ought not to be very difficult to trace that motor-van," said Guerchard, in a musing tone. "At any rate, its movements ought to be easy enough to follow up till about six. Then, of course, there would be a good many others about, delivering goods."
 
"You seem to have all the possible information you can want at your finger-ends," said the Duke, in an admiring tone.
 
"I suppose I know the life of Paris as well as anybody," said Guerchard.
 
They were silent for a while. Then Germaine's maid, Irma, came into the room and said:
 
"If you please, your Grace, Mademoiselle Kritchnoff would like to speak to you for a moment."
 
"Oh? Where is she?" said the Duke.
 
"She's in her room, your Grace."
 
"Oh, very well, I'll go up to her," said the Duke. "I can speak to her in the library."
 
He rose and was going towards the door when Guerchard stepped forward, barring his way, and said, "No, your Grace."
 
"No? Why?" said the Duke haughtily.
 
"I beg you will wait a minute or two till I've ha............