Thereupon a terrible anguish covered him with a cold sweat.  Supposing the detectives had ceased to watch the upper floors and confined themselves to spending the night in the rooms on the ground floor?

He madly took a brick and struck it repeatedly against the stone that closed the entrance, hoping that the noise would spread through the house.  But an avalanche of small stones, loosened by the blows, at once fell upon him, knocking him down again and fixing him where he lay.

“Help!  Help!”

More silence—­a great, ruthless silence.

“Help!  Help!”

He felt that his shouts did not penetrate the walls that stifled him.  Besides, his voice was growing fainter and fainter, producing a hoarse groan that died away in his strained throat.

He ceased his cries and again listened, with all his anxious attention, to the great silence that surrounded as with layers of lead the stone coffin in which he lay imprisoned.  Still nothing, not a sound.  No one would come, no one could come to his assistance.

He continued to be haunted by Florence’s name and image.  And he thought also of Marie Fauville, whom he had promised to save.  But Marie would die of starvation.  And, like her, like Gaston Sauverand and so many others, he in his turn was the victim of this monstrous horror.

An incident occurred to increase his dismay.  All of a sudden his electric lantern, which he had left alight to dispel the terrors of the darkness, went out.  It was eleven o’clock at night.

He was overcome with a fit of giddiness.  He could hardly breathe in the close and vitiated air.  His brain suffered, as it were, a physical and exceedingly painful ailment, from the repetition of images that seemed to encrust themselves there; and it was always Florence’s beautiful features or Marie’s livid face.  And, in his distraught brain, while Marie lay dying, he heard the explosion at the Fauvilles’ house and saw the Prefect of Police and Mazeroux lying hideously mutilated, dead.

A numbness crept over him.  He fell into a sort of swoon, in which he continued to stammer confused syllables: 

“Florence—­Marie—­Marie—­”

CHAPTER THIRTEEN

THE EXPLOSION

The fourth mysterious letter!  The fourth of those letters “posted by the devil and delivered by the devil,” as one of the newspapers expressed it!

We all of us remember the really extraordinary agitation of the public as the night of the twenty-fifth of May drew near.  And fresh news increased this interest to a yet higher degree.

People heard in quick succession of the arrest of Sauverand, the flight of his accomplice, Florence Levasseur, Don Luis Perenna’s secretary, and the inexplicable disappearance of Perenna himself, whom they insisted, for the best of reasons, on identifying with Arsene Lupin.