Filleul had arrived, Ganimard announced the capture which he had made. The prisoner was brought downstairs. It was Isidore Beautrelet.

“M. Isidore Beautrelet!” exclaimed M. Filleul with an air of rapture, holding out both his hands to the newcomer. “What a delightful surprise! Our excellent amateur detective here! And at our disposal too! Why, it’s a windfall!—M. Chief-inspector, allow me to introduce to you M. Isidore Beautrelet, a sixth-form pupil at the Lycee Janson-de-Sailly.”

Ganimard seemed a little nonplussed. Isidore made him a very low bow, as though he were greeting a colleague whom he knew how to esteem at his true value, and, turning to M. Filleul:

“It appears, Monsieur le Juge d’Instruction, that you have received a satisfactory account of me?”

“Perfectly satisfactory! To begin with, you were really at Veules-les-Roses at the time when Mlle. de Saint-Veran thought she saw you in the sunk road. I dare say we shall discover the identity of your double. In the second place, you are in very deed Isidore Beautrelet, a sixth-form pupil and, what is more, an excellent pupil, industrious at your work and of exemplary behavior. As your father lives in the country, you go out once a month to his correspondent, M. Bernod, who is lavish in his praises of you.”

“So that—”

“So that you are free, M. Isidore Beautrelet.”

“Absolutely free?”

“Absolutely. Oh, I must make just one little condition, all the same. You can understand that I can’t release a gentleman who administers sleeping-draughts, who escapes by the window and who is afterward caught in the act of trespassing upon private property. I can’t release him without a compensation of some kind.”

“I await your pleasure.”

“Well, we will resume our interrupted conversation and you shall tell me how far you have advanced with your investigations. In two days of liberty, you must have carried them pretty far?” And, as Ganimard was preparing to go, with an affectation of contempt for that sort of practice, the magistrate cried, “Not at all, M. Inspector, your place is here—I assure you that M. Isidore Beautrelet is worth listening to. M. Isidore Beautrelet, according to my information, has made a great reputation at the Lycee Janson-de-Sailly as an observer whom nothing escapes; and his schoolfellows, I hear, look upon him as your competitor and a rival of Holmlock Shears!”

“Indeed!” said Ganimard, ironically.

“Just so. One of them wrote to me, ‘If Beautrelet declares that he knows, you must believe him; and, whatever he says, you may be sure that it is the exact expression of the truth.’ M. Isidore Beautrelet, now or never is the time to vindicate the confidence of your friends. I beseech you, give us the exact expression of the truth.”

Isidore listened with a smile and replied:

“Monsieur le Juge d’Instruction, you are very cruel. You make fun of poor schoolboys who amuse themselves as best they can. You are quite right, however, and I will give you no further reason to laugh at me.”

“The fact is that you know nothing, M. Isidore Beautrelet.”

“Yes, I confess in all humility that I know nothing.