Burke follows a mournful song, an odd-looking key and an elusive young girl in white, after industrial designer Avery Lord is stabbed to death. The suspects are all his current clients: a playgirl whose compact is found at the crime scene, a hot-headed health food producer, a dishonest building contractor, and an auto manufacturer who dotes on his ""ferocious"" pet. Burke is knocked unconscious while chasing the girl in white through the fog one night outside Lord's mansion, or did he just imagine her? A distinctive piece of jewelry helps solve the case.