He beckoned to Cardona. With the detective at his side, Blake tapped four times against the wall. There was no response. He tapped harder. Cardona was astounded as the wall slid away; then, coming to his senses, he rushed into the next room.
An old man was raising his head from a desk. As his wild eyes saw the attackers, he seized a revolver that lay before him. Blake made a headlong dive as the old man rose. His quick hand caught the wrist that held the revolver and turned it aside just as the maniac pressed the trigger.
Blake was trying to capture the man alive, but Cardona spoiled the plan. Seeing the threat, the detective fired instinctively, and his bullets crashed into Zachary Shellmann’s brain.
The old man dropped dead, his wizened body sprawled in a pitiful heap.
“Double Z!” shouted Cardona. “Double Z! We’ve got him! We’ve got him!”
The detective’s eager eyes were taking in the scene — the earphones and the mouthpiece, the pile of clippings. He forgot the body and shoved a sheet of paper into a rickety typewriter in the corner. He struck off a line of letters and studied them.
“This looks like it!” he cried.
The keen eyes of Terry Blake were noting the typed characters. A frown appeared upon his forehead; then a gleam of understanding. The letters were identical to those of the Double Z notes.
Blake swung into the other room.
“Go in there and help Cardona,” he said to the detectives. “I’ll watch this man.”