The Prefect pursued his way toward Versailles in anxious expectancy. Each moment he thought to see the blue signal flash from the various cars which passed him. When it came, his men were to spring up, and at once bring the other car to a standstill by firing their guns, heavily charged with buckshot, at its wheels. A punctured tire, and the thing was done. His men, assisted by the chauffeur, would then overpower the occupants of the other car before they could realize what had happened. In it they hoped to find the child.
The plan was well conceived; but unfortunately it did not work. Whatever the reason, none of the cars which passed the Prefect on his way to Versailles displayed the telltale blue light. All seemed but peaceable automobilists, intent on reaching Paris and its restaurants as quickly as possible. Had his disguise been penetrated? He could not believe it. He returned to the Prefecture in great disgust, wondering in what way matters had gone wrong.
Grace was waiting for him, an eager smile on her face. "Here is the money," she said, placing the package on his desk. "Did you get the men?"
"No." The Prefect flung himself into a chair. "They did not signal."
"But why, I wonder?" The failure of her plan was extremely annoying.
"I can think of but one reason. There must have been some way in which these fellows knew the Stapleton car when they approached it—some signal, perhaps, that I was unable to give."
"But no such signal was mentioned in the instructions I brought to Mr. Stapleton. He gave none, as we approached him."
"Did you observe anything peculiar about the appearance of his car, anything that might have served as a clue to enable these fellows to recognize it, even in the dark, with certainty?"
Grace thought a moment, then her face fell. "There was one thing that I noticed as Mr. Stapleton's car came up to us; but I am afraid I failed to realize its significance at the time."
"What was it?"