Their electric torches flashed, and the roof was bathed in light. There was nothing behind which a person could hide, except two chimneys. The officers approached the chimneys, carefully, ready for instant combat. They circled them—and found nobody.
"He's here—got to be here!" the chief cried.
They rushed to all the fire escapes and found that nobody was on them. They shouted to officers in the street below, and were told that the fire escapes had not been used. They searched every square foot of the roof, looked along the parapet, found nobody.
"I tell you that crook's got to be here!" the chief shouted. "How could he get away?"
"Airplane," one of the detectives suggested.
"Don't be an ass!" the chief shrieked. "An airplane makes a lot of noise. And it wouldn't be easy to pick up a man from a roof in the dark, you fool! The only way it could be done would be to trail a rope and let him grab it, and that would mean a dead man on the pavement below. You ass, an airplane travels with speed!"
"Well, he doesn't seem to be here," Verbeck offered.
"But where could he have gone?" the chief cried. "Even the Black Star can't make himself invisible at will!"
Then they heard the Black Star laugh derisively.
They flashed their torches and again searched the roof. Once more they heard the laugh. Now it seemed to be to one side of them, and now to another. Above them, behind them, in front of them they heard it.