Don Luis recognized the Prefect of Police by his voice; and the question put by the Prefect told him, first, that Mazeroux had been released from the dark closet where he had bound him up, and, secondly, that the sergeant was in the next room. Fortunately, the sliding panel had worked without the least sound; and Don Luis was able to overhear the conversation between the two men.

"No, nothing new, Monsieur le Prefet," replied Mazeroux.

"That's funny. The confounded fellow must be somewhere. Or can he have got away over the roof?"

"Impossible, Monsieur le Prefet," said a third voice, which Don Luis recognized as that of Weber, the deputy chief detective. "Impossible. We made certain yesterday, that unless he has wings--"

"Then what do you think, Weber?"

"I think, Monsieur le Prefet, that he is concealed in the house. This is an old house and probably contains some safe hiding-place--"

"Of course, of course," said M. Desmalions, whom Don Luis, peeping through the curtains, saw walking to and fro in front of the alcove.

"You're right; and we shall catch him in his burrow. Only, is it really necessary?"

"Monsieur le Prefet!"

"Well, you know my opinion on the subject, which is also the Prime Minister's opinion. Unearthing Lupin would be a blunder which we should end by regretting. After all, he's become an honest man, you know; he's useful to us and he does no harm--"

"No harm, Monsieur le Prefet? Do you think so?" said Weber stiffly.

M. Desmalions burst out laughing.

"Oh, of course, yesterday's trick, the telephone trick! You must admit it was funny. The Premier had to hold his sides when I told him of it."

"Upon my word, I see nothing to laugh at!"

"No, but, all the same, the rascal is never at a loss. Funny or not, the trick was extraordinarily daring. To cut the telephone wire before your eyes and then blockade you behind that iron curtain! By the way, Mazeroux, you must get the telephone repaired this morning, so as to keep in touch with the office. Have you begun your search in these two rooms?"

"As you ordered, Monsieur le Prefet. The deputy chief and I have been hunting round for the last hour."

"Yes," said M. Desmalions, "that Florence Leva.s.seur strikes me as a troublesome creature. She is certainly an accomplice. But what were her relations with Sauverand and what was her connection with Don Luis Perenna? That's what I should like to know. Have you discovered nothing in her papers?"

"No, Monsieur le Prefet," said Mazeroux. "Nothing but bills and tradesmen's letters."

"And you, Weber?"

"I've found something very interesting, Monsieur le Prefet."

Weber spoke in a triumphant tone, and, in answer to M. Desmalions's question, went on:

"This is a volume of Shakespeare, Monsieur le Prefet, Volume VIII. You will see that, contrary to the other volumes, the inside is empty and the binding forms a secret receptacle for hiding doc.u.ments."

"Yes. What sort of doc.u.ments?"

"Here they are: sheets of paper, blank sheets, all but three. One of them gives a list of the dates on which the mysterious letters were to appear."

"Oho!" said M. Desmalions. "That's a crushing piece of evidence against Florence Leva.s.seur. And also it tells us where Don Luis got his list from."

Perenna listened with surprise: he had utterly forgotten this particular; and Gaston Sauverand had made no reference to it in his narrative. And yet it was a strange and serious detail. From whom had Florence received that list of dates?

"And what's on the other two sheets?" asked M. Desmalions.

Don Luis p.r.i.c.ked up his ears. Those two other sheets had escaped his attention on the day of his interview with Florence in this room.

"Here is one of them," said Weber.

M. Desmalions took the paper and read:

"Bear in mind that the explosion is independent of the letters, and that it will take place at three o'clock in the morning."

"Yes," he said, "the famous explosion which Don Luis foretold and which is to accompany the fifth letter, as announced on the list of dates.

Tush! We have plenty of time, as there have been only three letters and the fourth is due to-night. Besides, blowing up that house on the Boulevard Suchet would be no easy job, by Jove! Is that all?"

"Monsieur le Prefet," said Weber, producing the third sheet, "would you mind looking at these lines drawn in pencil and enclosed in a large square containing some other smaller squares and rectangles of all sizes?

Wouldn't you say that it was the plan of a house?"

"Yes, I should."

"It is the plan of the house in which we are," declared Weber solemnly.

"Here you see the front courtyard, the main building, the porter's lodge, and, over there, Mlle. Leva.s.seur's lodge. From this lodge, a dotted line, in red pencil, starts zigzagging toward the main building. The commencement of this line is marked by a little red cross which stands for the room in which we are, or, to be more correct, the alcove. You will see here something like the design of a chimney, or, rather, a cupboard--a cupboard recessed behind the bed and probably hidden by the curtains."

"But, in that case, Weber," said M. Desmalions, "this dotted line must represent a pa.s.sage leading from this lodge to the main building. Look, there is also a little red cross at the other end of the line."

"Yes, Monsieur le Prefet, there is another cross. We shall discover later for certain what position it marks. But, meanwhile, and acting on a mere guess, I have posted some men in a small room on the second floor where the last secret meeting between Don Luis, Florence Leva.s.seur, and Gaston Sauverand was held yesterday. And, meanwhile, at any rate, we hold one end of the line and, through that very fact, we know Don Luis Perenna's retreat."

There was a pause, after which the deputy chief resumed in a more and more solemn voice:

"Monsieur le Prefet, yesterday I suffered a cruel outrage at the hands of that man. It was witnessed by our subordinates. The servants must be aware of it. The public will know of it before long. This man has brought about the escape of Florence Leva.s.seur. He tried to bring about the escape of Gaston Sauverand. He is a ruffian of the most dangerous type.

Monsieur le Prefet, I am sure that you will not refuse me leave to dig him out of his hole. Otherwise--otherwise, Monsieur le Prefet, I shall feel obliged to hand in my resignation."

"With good reasons to back it up!" said the Prefect, laughing. "There's no doubt about it; you can't stomach the trick of the iron curtain. Well, go ahead! It's Don Luis's own lookout; he's brought it on himself.

Mazeroux, ring me up at the office as soon as the telephone is put right.

And both of you meet me at the Fauvilles' house this evening. Don't forget it's the night for the fourth letter."

"There won't be any fourth letter, Monsieur le Prefet," said Weber.

"Why not?"

"Because between this and then Don Luis will be under lock and key."

"Oh, so you accuse Don Luis also of--"

Don Luis did not wait to hear more. He softly retreated to the cupboard, took hold of the panel and pushed it back without a sound.

So his hiding-place was known!

"By Jingo," he growled, "this is a bit awkward! I'm in a nice plight!"