On hearing the word “investigation,” neither the Duc de Sairmeuse nor the Marquis de Courtornieu could repress a slight shudder.

They could not ignore the fact that their reputations were at stake, and that the merest trifle might disclose the truth.  A precaution neglected, the most insignificant detail, a word, a gesture might ruin their ambitious hopes forever.

They trembled to think that this officer might be a man of unusual shrewdness, who had suspected their complicity, and was impatient to verify his presumptions.

No, the old lieutenant had not the slightest suspicion.  He had spoken on the impulse of the moment, merely to give vent to his displeasure.  He was not even keen enough to remark the rapid glance interchanged between the marquis and the duke.

Martial noticed this look, however, and with a politeness too studied not to be ridicule, he addressed the lieutenant: 

“Yes, we must institute an investigation; that suggestion is as shrewd as it is opportune,” he remarked.

The old officer turned away with a muttered oath.

“That coxcomb is poking fun at me,” he thought; “and he and his father and that prig deserve—­but what is one to do?”

In spite of his bold remark, Martial felt that he must not incur the slightest risk.

To whom must the charge of this investigation be intrusted?  To the duke and to the marquis, of course, since they were the only persons who would know just how much to conceal, and just how much to disclose.

They began their task immediately, with an empressement which could not fail to silence all doubts, in case any existed in the minds of their subordinates.

But who could be suspicious?  The success of the plot had been all the more certain from the fact that the baron’s escape seemed likely to injure the interests of the very parties who had favored it.

Martial thought he knew the details of the escape as exactly as the fugitives themselves.  He had been the author, even if they had been the actors, of the drama of the preceding night.

He was soon obliged to admit that he was mistaken in this opinion.

The investigation revealed facts which seemed incomprehensible to him.

It was evident that the Baron d’Escorval and Corporal Bavois had been compelled to accomplish two successive descents.

To do this the prisoners had realized (since they had succeeded) the necessity of having two ropes.  Martial had provided them; the prisoners must have used them.  And yet only one rope could be found—­the one which the peasant woman had perceived hanging from the rocky platform, where it was made fast to an iron crowbar.

From the window to the platform, there was no rope.

“This is most extraordinary!” murmured Martial, thoughtfully.

“Very strange!” approved M. de Courtornieu.

“How the devil could they have reached the base of the tower?”