He was a prisoner.  In a sudden fit of rage he banged at the metal with his fists.  He remembered that Mlle. Levasseur was in the study.  If she had not yet left the room—­and surely she could not have left it when the thing happened—­she would hear the noise.  She was bound to hear it.  She would be sure to come back, give the alarm, and rescue him.

He listened.  He shouted.  No reply.  His voice died away against the walls and ceiling of the box in which he was shut up, and he felt that the whole house—­drawing-rooms, staircases, and passages—­remained deaf to his appeal.

And yet ... and yet ...  Mlle. Levasseur—­

“What does it mean?” he muttered.  “What can it all mean?”

And motionless now and silent, he thought once more of the girl’s strange attitude, of her distraught face, of her haggard eyes.  And he also began to wonder what accident had released the mechanism which had hurled the formidable iron curtain upon him, craftily and ruthlessly.

CHAPTER SIX

THE MAN WITH THE EBONY WALKING-STICK

A group consisting of Deputy Chief Detective Weber, Chief Inspector Ancenis, Sergeant Mazeroux, three inspectors, and the Neuilly commissary of police stood outside the gate of No. 8 Boulevard Richard-Wallace.

Mazeroux was watching the Avenue de Madrid, by which Don Luis would have to come, and began to wonder what had happened; for half an hour had passed since they telephoned to each other, and Mazeroux could find no further pretext for delaying the work.

“It’s time to make a move,” said Weber.  “The housekeeper is making signals to us from the window:  the joker’s dressing.”

“Why not nab him when he comes out?” objected Mazeroux.  “We shall capture him in a moment.”

“And if he cuts off by another outlet which we don’t know of?” said the deputy chief.  “You have to be careful with these beggars.  No, let’s beard him in his den.  It’s more certain.”

“Still—­”

“What’s the matter with you, Mazeroux?” asked the deputy chief, taking him on one side.  “Don’t you see that our men are getting restive?  They’re afraid of this sportsman.  There’s only one way, which is to set them on him as if he were a wild beast.  Besides, the business must be finished by the time the Prefect comes,”

“Is he coming?”

“Yes.  He wants to see things for himself.  The whole affair interests him enormously.  So, forward!  Are you ready, men?  I’m going to ring.”

The bell sounded; and the housekeeper at once came and half opened the gate.

Although the orders were to observe great quiet, so as not to alarm the enemy too soon, the fear which he inspired was so intense that there was a general rush; and all the detectives crowded into the courtyard, ready for the fight.  But a window opened and some one cried from the second floor: