"Wasn't it in her room, in a volume of Shakespeare, that doc.u.ments were found relating to M. Fauville's arrangements about the letters and the explosion? And then--"

Mazeroux interrupted himself, frightened by the look in Don Luis's eyes and realizing that the chief was fonder of the girl then ever. Guilty or not, she inspired him with the same pa.s.sion.

"All right," said Mazeroux, "we'll say no more about it. The future will bear me out, you'll see."

The days pa.s.sed. Mazeroux called as often as possible, or else telephoned to Don Luis all the details of the two inquiries that were being pursued at Saint-Lazare and at the Sante Prison.

Vain inquiries, as we know. While Don Luis's statements relating to the electric chandelier and the automatic distribution of the mysterious letters were found to be correct, the investigation failed to reveal anything about the two suicides.

At most, it was ascertained that, before his arrest, Sauverand had tried to enter into correspondence with Marie through one of the tradesmen supplying the infirmary. Were they to suppose that the phial of poison and the hypodermic syringe had been introduced by the same means? It was impossible to prove; and, on the other hand, it was impossible to discover how the newspaper cuttings telling of Marie's suicide had found their way into Gaston Sauverand's cell.

And then the original mystery still remained, the unfathomable mystery of the marks of teeth in the apple. M. Fauville's posthumous confession acquitted Marie. And yet it was undoubtedly Marie's teeth that had marked the apple. The teeth that had been called the teeth of the tiger were certainly hers. Well, then!

In short, as Mazeroux said, everybody was groping in the dark, so much so that the Prefect, who was called upon by the will to a.s.semble the Mornington heirs at a date not less than three nor more than four months after the testator's decease, suddenly decided that the meeting should take place in the course of the following week and fixed it for the ninth of June.

He hoped in this way to put an end to an exasperating case in which the police displayed nothing but uncertainty and confusion. They would decide about the inheritance according to circ.u.mstances and then close the proceedings. And gradually people would cease to talk about the wholesale slaughter of the Mornington heirs; and the mystery of the teeth of the tiger would be gradually forgotten.

It was strange, but these last days, which were restless and feverish like all the days that come before great battles--and every one felt that this last meeting meant a great battle--were spent by Don Luis in an armchair on his balcony in the Rue de Rivoli, where he sat quietly smoking cigarettes, or blowing soap-bubbles which the wind carried toward the garden of the Tuileries.

Mazeroux could not get over it.

"Chief, you astound me! How calm and careless you look!"

"I am calm and careless, Alexandre."

"But what do you mean? Doesn't the case interest you? Don't you intend to avenge Mme. Fauville and Sauverand? You are openly accused and you sit here blowing soap-bubbles!"

"There's no more delightful pastime, Alexandre."

"Shall I tell you what I think, Chief? You've discovered the solution of the mystery!"

"Perhaps I have, Alexandre, and perhaps I haven't."

Nothing seemed to excite Don Luis. Hours and hours pa.s.sed; and he did not stir from his balcony. The sparrows now came and ate the crumbs which he threw to them. It really seemed as if the case was coming to an end for him and as if everything was turning out perfectly.

But, on the day of the meeting, Mazeroux entered with a letter in his hand and a scared look on his face.

"This is for you, Chief. It was addressed to me, but with an envelope inside it in your name. How do you explain that?"

"Quite easily, Alexandre. The enemy is aware of our cordial relations; and, as he does not know where I am staying--"

"What enemy?"

"I'll tell you to-morrow evening."

Don Luis opened the envelope and read the following words, written in red ink:

"There's still time, Lupin. Retire from the contest. If not, it means your death, too. When you think that your object is attained, when your hand is raised against me and you utter words of triumph, at that same moment the ground will open beneath your feet. The place of your death is chosen. The snare is laid. Beware, Lupin."

Don Luis smiled.

"Good," he said. "Things are taking shape,"

"Do you think so, Chief?"

"I do. And who gave you the letter?"

"Ah, we've been lucky for once, Chief! The policeman to whom it was handed happened to live at Les Ternes, next door to the bearer of the letter. He knows the fellow well. It was a stroke of luck, wasn't it?"

Don Luis sprang from his seat, radiant with delight.

"What do you mean? Out with it! You know who it is?"

"The chap's an indoor servant employed at a nursing-home in the Avenue des Ternes."

"Let's go there. We've no time to lose."

"Splendid, Chief! You're yourself again."

"Well, of course! As long as there was nothing to do I was waiting for this evening and resting, for I can see that the fight will be tremendous. But, as the enemy has blundered at last, as he's given me a trail to go upon, there's no need to wait, and I'll get ahead of him.

Have at the tiger, Mazeroux!"

It was one o'clock in the afternoon when Don Luis and Mazeroux arrived at the nursing-home in the Avenue des Ternes. A manservant opened the door.

Mazeroux nudged Don Luis. The man was doubtless the bearer of the letter.

And, in reply to the sergeant's questions, he made no difficulty about saying that he had been to the police office that morning.

"By whose orders?" asked Mazeroux.

"The mother superior's."

"The mother superior?"

"Yes, the home includes a private hospital, which is managed by nuns."

"Could we speak to the superior?"

"Certainly, but not now: she has gone out."

"When will she be in?"

"Oh, she may be back at any time!"

The man showed them into the waiting-room, where they spent over an hour.

They were greatly puzzled. What did the intervention of that nun mean?