The doctor nodded and continued his examination, while the other three stood where they were, looking keenly about them. It was obvious that when death overtook Mr. Copperdock he had been preparing for bed. His coat, waistcoat, shirt and vest lay on a chair, and the basin on the washing stand was half full of soapy water. A towel lay on the floor near it.

The minutes seemed to pass with leaden slowness until a faint throbbing reached their ears, which rapidly grew in intensity until it resolved itself into the sound of a motorcycle. The noise ceased suddenly as it reached the door, and in a few seconds Inspector Whyland appeared, half dressed, with a stern expression on his face.

“How did this happen, Waters?” he enquired sharply, turning to the detective.

“I don’t know, sir,” replied the latter. “I’ve been watching the house all the evening⁠—”