“All right, thank you, Miss Keate,” came a voice at my elbow. It was O’Leary, his hat gone, his hair ruffled, his eyes shining like phosphorescent flashes on a deep-lying sea. “Come with me, please,” he said.

“Was the fuse burned out?” asked O’Leary as we met Maida, who was hurrying to answer the signals.

She shook her head. Her eyes were hollow and dark and her face as white as her cap.

“The main switch had been pulled out.”

“What I expected,” muttered O’Leary, as we sped along the corridor.

Lights were gleaming from the north wing, and the night-duty nurses from that wing were clustered in a frightened group in the main hall. As they saw us they ran forward.

“What was it, Miss Keate—we heard a shot—what has happened?” And down the stairs tumbled several nurses in uniforms and kimonos and Miss Dotty with her hair in paper curlers and her eyes distracted.

O’Leary paid no attention to them. I followed him into the general office. He rapped sharply, first at Dr. Hajek’s door, then at the door of the inner office. Then he put his hand on the latch of the door to the inner office and pushed. It was not locked and opened readily; the light from the office streamed through the door.

“O’Leary! What has happened? What is it?” Dr. Balman, his eyes blinking anxiously in the light, was tossing back the covers and springing from his bed.

“There has been another murder in Room 18,” said O’Leary.