The Case of the Crimson Kiss — Erle Stanley Gardner

"It's a chance we shouldn't take," Perry Mason said, "but I'm going to take a peek, just for luck."

Perry Mason and Della Street walked softly into the strange apartment. The blazing lights of the living room showed the sprawled body of a man on the floor, and the drinking glass which had rolled from his dead fingers.

Della, clinging to Mason's arm, saw the overturned chair and another empty glass on the table.

In the middle of the man's balding forehead was imprinted a crimson kiss!