Was M. Lecoq really angry, or pretending to be? Fanferlot, who knew him well, was puzzled to know whether all this indignation was real.

“If you were only skilful,” he continued, “but no: you wish to be master, and you are not fit to be a journeyman.”

“You are right, patron,” said Fanferlot, piteously, for he saw that it was useless for him to deny anything. “But how could I go about an affair like this, where there was not even a trace or sign to start from?”

M. Lecoq shrugged his shoulders.

“You are an ass! Why, don’t you know that on the very day you were sent for with the commissary to verify the robbery, you held—I do not say certainly, but very probably held—in your great stupid hands the means of knowing which key had been used when the money was stolen?”

“How! What!”

“You want to know, do you? I will tell you. Do you remember the scratch you discovered on the safe-door? You were so struck by it, that you exclaimed directly you saw it. You carefully examined it, and were convinced that it was a fresh scratch, only a few hours old. You thought, and rightly too, that this scratch was made at the time of the theft. Now, with what was it made? Evidently with a key. That being the case, you should have asked for the keys both of the banker and the cashier. One of them would have had some particles of the hard green paint sticking to it.”

Fanferlot listened with open mouth to this explanation. At the last words, he violently slapped his forehead with his hand, and cried out:

“Imbecile! Imbecile!”

“You have rightly named yourself,” said M. Lecoq. “Imbecile! This proof stares you right in the face, and you don’t see it! This scratch is the sole and only clew to work the case upon, and you must go and lose the traces of it. If I find the guilty party, it will be by means of this scratch; and I am determined that I will find him.”