"What is it, Monsieur le Prefet?"

"Why, look here, a blank ... sheet of paper! That's all the envelope contains!"

"Impossible!"

"See for yourself--a plain sheet folded in four, with not a word on it."

"But Verot told me in so many words that he had said in that letter all that he knew about the case."

"He told you so, no doubt, but there you are! Upon my word, if I didn't know Inspector Verot, I should think he was trying to play a game with me."

"It's a piece of carelessness, Monsieur le Prefet, at the worst."

"No doubt, a piece of carelessness, but I'm surprised at him. It doesn't do to be careless when the lives of two people are at stake. For he must have told you that there is a double murder planned for to-night?"

"Yes, Monsieur le Prefet, and under particularly alarming conditions; infernal was the word he used."

M. Desmalions was walking up and down the room, with his hands behind his back. He stopped at a small table.

"What's this little parcel addressed to me? 'Monsieur le Prefet de Police--to be opened in case of accident.'"

"Oh, yes," said the secretary, "I was forgetting! That's from Inspector Verot, too; something of importance, he said, and serving to complete and explain the contents of the letter."

"Well," said M. Desmalions, who could not help laughing, "the letter certainly needs explaining; and, though there's no question of 'accident,' I may as well open the parcel."

As he spoke, he cut the string and discovered, under the paper, a box, a little cardboard box, which might have come from a druggist, but which was soiled and spoiled by the use to which it had been put.

He raised the lid. Inside the box were a few layers of cotton wool, which were also rather dirty, and in between these layers was half a cake of chocolate.

"What the devil does this mean?" growled the Prefect in surprise.

He took the chocolate, looked at it, and at once perceived what was peculiar about this cake of chocolate, which was also undoubtedly the reason why Inspector Verot had kept it. Above and below, it bore the prints of teeth, very plainly marked, very plainly separated one from the other, penetrating to a depth of a tenth of an inch or so into the chocolate. Each possessed its individual shape and width, and each was divided from its neighbours by a different interval. The jaws which had started eating the cake of chocolate had dug into it the mark of four upper and five lower teeth.

M. Desmalions remained wrapped in thought and, with his head sunk on his chest, for some minutes resumed his walk up and down the room, muttering:

"This is queer ... There's a riddle here to which I should like to know the answer. That sheet of paper, the marks of those teeth: what does it all mean?"

But he was not the man to waste much time over a mystery which was bound to be cleared up presently, as Inspector Verot must be either at the police office or somewhere just outside; and he said to his secretary:

"I can't keep those five gentlemen waiting any longer. Please have them shown in now. If Inspector Verot arrives while they are here, as he is sure to do, let me know at once. I want to see him as soon as he comes.

Except for that, see that I'm not disturbed on any pretext, won't you?"

Two minutes later the messenger showed in Maitre Lepertuis, a stout, red-faced man, with whiskers and spectacles, followed by Archibald Bright, the Secretary of Emba.s.sy, and Caceres, the Peruvian attache. M.

Desmalions, who knew all three of them, chatted to them until he stepped forward to receive Major Comte d'Astrignac, the hero of La Choua, who had been forced into premature retirement by his glorious wounds. The Prefect was complimenting him warmly on his gallant conduct in Morocco when the door opened once more.

"Don Luis Perenna, I believe?" said the Prefect, offering his hand to a man of middle height and rather slender build, wearing the military medal and the red ribbon of the Legion of Honour.

The newcomer's face and expression, his way of holding himself, and his very youthful movements inclined one to look upon him as a man of forty, though there were wrinkles at the corners of the eyes and on the forehead, which perhaps pointed to a few years more. He bowed.

"Yes, Monsieur le Prefet."

"Is that you, Perenna?" cried Comte d'Astrignae. "So you are still among the living?"

"Yes, Major, and delighted to see you again."

"Perenna alive! Why, we had lost all sight of you when I left Morocco! We thought you dead."

"I was a prisoner, that's all."

"A prisoner of the tribesmen; the same thing!"

"Not quite, Major; one can escape from anywhere. The proof stands before you."

The Prefect of Police, yielding to an irresistible attraction to resist, spent some seconds in examining that powerful face, with the smiling glance, the frank and resolute eyes, and the bronzed complexion, which looked as if it had been baked and baked again by the sun.

Then, motioning to his visitors to take chairs around his desk, M.

Desmalions himself sat down and made a preliminary statement in clear and deliberate tones:

"The summons, gentlemen, which I addressed to each of you, must have appeared to you rather peremptory and mysterious. And the manner in which I propose to open our conversation is not likely to diminish your surprise. But if you will attach a little credit to my method, you will soon realize that the whole thing is very simple and very natural. I will be as brief as I can."

He spread before him the bundle of doc.u.ments prepared for him by his secretary and, consulting his notes as he spoke, continued:

"Over fifty years ago, in 1860, three sisters, three orphans, Ermeline, Elizabeth, and Armande Roussel, aged twenty-two, twenty, and eighteen respectively, were living at Saint-Etienne with a cousin named Victor, who was a few years younger. The eldest, Ermeline, was the first to leave Saint-Etienne. She went to London, where she married an Englishman of the name Mornington, by whom she had a son, who was christened Cosmo.

"The family was very poor and went through hard times. Ermeline repeatedly wrote to her sisters to ask for a little a.s.sistance. Receiving no reply, she broke off the correspondence altogether. In 1870 Mr. and Mrs. Mornington left England for America. Five years later they were rich. Mr. Mornington died in 1878; but his widow continued to administer the fortune bequeathed to her and, as she had a genius for business and speculation, she increased this fortune until it attained a colossal figure. At her decease, in 1900, she left her son the sum of four hundred million francs."

The amount seemed to make an impression on the Prefect's hearers. He saw the major and Don Luis Perenna exchange a glance and asked:

"You knew Cosmo Mornington, did you not?"

"Yes, Monsieur le Prefet," replied Comte d'Astrignac. "He was in Morocco when Perenna and I were fighting there."

"Just so," said M. Desmalions. "Cosmo Mornington had begun to travel about the world. He took up the practise of medicine, from what I hear, and, when occasion offered, treated the sick with great skill and, of course, without charge. He lived first in Egypt and then in Algiers and Morocco. Last year he settled down in Paris, where he died four weeks ago as the result of a most stupid accident."

"A carelessly administered hypodermic injection, was it not, Monsieur le Prefet?" asked the secretary of the American Emba.s.sy. "It was mentioned in the papers and reported to us at the emba.s.sy."

"Yes," said Desmalions. "To a.s.sist his recovery from a long attack of influenza which had kept him in bed all the winter, Mr. Mornington, by his doctor's orders, used to give himself injections of glycero-phosphate of soda. He must have omitted the necessary precautions on the last occasion when he did so, for the wound was poisoned, inflammation set in with lightning rapidity, and Mr. Mornington was dead in a few hours."

The Prefect of Police turned to the solicitor and asked:

"Have I summed up the facts correctly, Maitre Lepertuis?"

"Absolutely, Monsieur le Prefet."

M. Desmalions continued: