Psychotic mother's boy Bruno Anthony meets famous tennis professional Guy Haines on a train. Guy wants to move into a career in politics and has been dating a senator's daughter (Ann Morton) while awaiting a divorce from his wife. Bruno wants to kill his father but knows he will be caught because he has a motive. Bruno dreams up a crazy scheme in which he and Guy exchange murders. Guy takes this as a joke, but Bruno is serious and takes things into his own hands.