"The electric headlight on the side nearest to me was working very badly. In fact, it seemed to be almost out. The other was burning brilliantly."
The Prefect sprang to his feet. "Sacré!" he exclaimed. "Of course. The thing is as plain as the nose on your face!"
"But who—"
"François! The fellow is in this thing up to his neck. He claims to have been asleep when the boy was stolen. He drives the car which brings you back, after your abduction. He, disguised, steals the box of cigarettes. He fixes the lights so that the kidnappers are advised, not only beyond any doubt that they are signaling the right car, but that all is safe—that Monsieur Stapleton has no detectives or members of the police hidden in his tonneau. The thing is perfectly clear. Believe me, my child, had there been anyone in that car with Mr. Stapleton, those lights would have both been burning with equal brightness, as mine were. They did not give me the signal, when they passed me, because the lights failed to tell them that all was well."
Grace looked up quickly. "Then, if that is true, François knew that Mr. Stapleton had thrown the money into the wrong car."
"Undoubtedly, and by this time, no doubt, his confederates know it as well. Naturally the child has not been delivered. We are just where we were before."
"You will arrest François at once, I suppose."
"No. It will be useless. By leaving him free, we may learn something. By locking him up, with no tangible evidence against him, we accomplish nothing at all."
"Then what do you advise?"
"You will return the money to Mr. Stapleton at once. You can tell him, if you wish, how it came into your possession. He will be furious, of course; but he must understand that the capture of these scoundrels is quite as important to the city of Paris as the recovery of his son. We have done our best, and failed. We must try again."