M. Desmalions asked:

"Will you let me see the necklace, Madame?"

"Certainly. It is with my other jewels, in my wardrobe. I will go for it."

"Pray don't trouble, Madame. Does your maid know the necklace?"

"Quite well."

"In that case, Sergeant Mazeroux will tell her what is wanted."

Not a word was spoken during the few minutes for which Mazeroux was absent. Mme. Fauville seemed absorbed in her grief. M. Desmalions kept his eyes fixed on her.

The sergeant returned, carrying a very large box containing a number of jewel-cases and loose ornaments.

M. Desmalions found the necklace, examined it, and realized, in fact, that the stones did not resemble the turquoise and that none of them was missing. But, on separating two jewel cases in order to take out a tiara which also contained blue stones, he made a gesture of surprise.

"What are these two keys?" he asked, pointing to two keys identical in shape and size with those which opened the lock and the bolt of the garden door.

Mme. Fauville remained very calm. Not a muscle of her face moved. Nothing pointed to the least perturbation on account of this discovery. She merely said:

"I don't know. They have been there a long time."

"Mazeroux," said M. Desmalions, "try them on that door."

Mazeroux did so. The door opened.

"Yes," said Mme. Fauville. "I remember now, my husband gave them to me.

They were duplicates of his own keys--"

The words were uttered in the most natural tone and as though the speaker did not even suspect the terrible charge that was forming against her.

And nothing was more agonizing than this tranquillity. Was it a sign of absolute innocence, or the infernal craft of a criminal whom nothing is able to stir? Did she realize nothing of the tragedy which was taking place and of which she was the unconscious heroine? Or did she guess the terrible accusation which was gradually closing in upon her on every side and which threatened her with the most awful danger? But, in that case, how could she have been guilty of the extraordinary blunder of keeping those two keys?

A series of questions suggested itself to the minds of all those present.

The Prefect of Police put them as follows:

"You were out, Madame, were you not, when the murders were committed?"

"Yes."

"You were at the opera?"

"Yes; and I went on to a party at the house of one of my friends, Mme.

d'Ersingen."

"Did your chauffeur drive you?"

"To the opera, yes. But I sent him back to his garage; and he came to fetch me at the party."

"I see," said M. Desmalions. "But how did you go from the opera to Mme.

d'Ersingen's?"

For the first time, Mme. Fauville seemed to understand that she was the victim of a regular cross-examination; and her look and att.i.tude betrayed a certain uneasiness. She replied:

"I took a motor cab."

"In the street?"

"On the Place de l'Opera."

"At twelve o'clock, therefore?"

"No, at half-past eleven: I left before the opera was over."

"You were in a hurry to get to your friend's?"

"Yes ... or rather--"

She stopped; her cheeks were scarlet; her lips and chin trembled; and she asked:

"Why do you ask me all these questions?"

"They are necessary, Madame. They may throw a light on what we want to know. I beg you, therefore, to answer them. At what time did you reach your friend's house?"

"I hardly know. I did not notice the time."

"Did you go straight there?"

"Almost."

"How do you mean, almost?"

"I had a little headache and told the driver to go up the Champs Elysees and the Avenue du Bois--very slowly--and then down the Champs Elysees again--"

She was becoming more and more embarra.s.sed. Her voice grew indistinct.

She lowered her head and was silent.

Certainly her silence contained no confession, and there was nothing ent.i.tling any one to believe that her dejection was other than a consequence of her grief. But yet she seemed so weary as to give the impression that, feeling herself lost, she was giving up the fight. And it was almost a feeling of pity that was entertained for this woman against whom all the circ.u.mstances seemed to be conspiring, and who defended herself so badly that her cross-examiner hesitated to press her yet further.

M. Desmalions, in fact, wore an irresolute air, as if the victory had been too easy, and as if he had some scruple about pursuing it.

Mechanically he observed Perenna, who pa.s.sed him a slip of paper, saying:

"Mme. d'Ersingen's telephone number."

M. Desmalions murmured: