The three men walked into the study. The doorway formed an entrance at one corner. The study was a long room, with a single window at the far end.

The window was open; but it was covered with an iron grating. It had a projecting sill, beneath which was a radiator. In front of the window lay the body of Silas Harshaw, sprawled face upward.

As the men approached, they saw a bloody wound in the old man’s chest.

A SINGLE bullet had ended the life of Silas Harshaw. Here, in this locked and secluded room, he had been shot to death. Cardona pointed to a door at the side of the room.

“That’s the bedroom,” he said. “It only has one door, opening off this room. It has two windows, both with gratings. Nothing in there. That’s the layout, commissioner.

“Old Harshaw very seldom let visitors in here. He usually met them in the outer room.”

Commissioner Weston turned to Professor Biscayne.

“Tell Cardona what you know about the place,” he said.

“I am familiar with this room,” declared Biscayne. “I visited Silas Harshaw here, perhaps a half dozen times, in the course of the last six months.

“I suppose that you have learned a great deal about him already; let me give you the information which I possess. Then you can check with what you have discovered.