THE door moved now. The flashlight went out. Beams of light came through the crack. Blake slid through. Cardona followed, but Blake had moved so rapidly that Cardona was left well behind.
Within the room the detective discovered the secret-service man, gun in hand, covering a startled Chinaman who had been sitting in a chair.
The captive was garbed in American clothes. He had risen when Blake had surprised him, and now stood half out of the chair, his hands above his head.
“Get your men,” whispered Blake.
Cardona summoned his detectives. At Blake’s order they pressed the muzzles of their guns against the Chinaman’s body.
“If he says one word,” ordered Blake, “shoot him. Not a sound — or we kill!”
The secret-service man went to the opposite wall. He ran his hands up and down from side to side. At last he found a spot that suited him. He looked at the Chinaman.
“Is it three taps or four?” he questioned.
Luke Froy did not reply.
“Come,” said Blake. “I heard you once when I was outside. It sounded like three taps” — the Chinaman’s lips curled almost imperceptibly, but Blake detected the motion as a suppressed smile — “but I’ll try four!”