Private eyes Randall and Hopkirk are investigating two-timing husband Kenneth Crisby as Marty Hopkirk prepares for his marriage to Jeannie Hurst. Performance artist Gordon Stylus also seeks their help as he believes his wife is suicidal. Marty is killed when a car, apparently driven by Mrs. Stylus, sweeps them both over a cliff. The killer is, in fact, Crisby and Marty's ghost comes to Jeff Randall's aid when Crisby threatens him. However, Marty is destined to remain a ghost with only Jeff being able to see him.