* * * * *

Hippolyte Fauville, civil engineer, lived on the Boulevard Suchet, near the fortifications, in a fair-sized private house having on its left a small garden in which he had built a large room that served as his study.  The garden was thus reduced to a few trees and to a strip of grass along the railings, which were covered with ivy and contained a gate that opened on the Boulevard Suchet.

Don Luis Perenna went with Mazeroux to the commissary’s office at Passy, where Mazeroux, on Perenna’s instructions, gave his name and asked to have M. Fauville’s house watched during the night by two policemen who were to arrest any suspicious person trying to obtain admission.  The commissary agreed to the request.

Don Luis and Mazeroux next dined in the neighbourhood.  At nine o’clock they reached the front door of the house.

“Alexandre,” said Perenna.

“Yes, Chief?”

“You’re not afraid?”

“No, Chief.  Why should I be?”

“Why?  Because, in defending M. Fauville and his son, we are attacking people who have a great interest in doing away with them and because those people seem pretty wide-awake.  Your life, my life:  a breath, a trifle.  You’re not afraid?”

“Chief,” replied Mazeroux, “I can’t say if I shall ever know what it means to be afraid.  But there’s one case in which I certainly shall never know.”

“What case is that, old chap?”

“As long as I’m by your side, Chief.”

And firmly he rang the bell.

CHAPTER THREE

A MAN DOOMED

The door was opened by a manservant.  Mazeroux sent in his card.

Hippolyte received the two visitors in his study.  The table, on which stood a movable telephone, was littered with books, pamphlets, and papers.  There were two tall desks, with diagrams and drawings, and some glass cases containing reduced models, in ivory and steel, of apparatus constructed or invented by the engineer.

A large sofa stood against the wall.  In one corner was a winding staircase that led to a circular gallery.  An electric chandelier hung from the ceiling.

Mazeroux, after stating his quality and introducing his friend Perenna as also sent by the Prefect of Police, at once expounded the object of their visit.

M. Desmalions, he said, was feeling anxious on the score of very serious indications which he had just received and, without waiting for the next day’s interview, begged M. Fauville to take all the precautions which his detectives might advise.

Fauville at first displayed a certain ill humour.

“My precautions are taken, gentlemen, and well taken.  And, on the other hand, I am afraid that your interference may do harm.”

“In what way?”

“By arousing the attention of my enemies and preventing me, for that reason, from collecting proofs which I need in order to confound them.”