Bruno Antony and Guy Haines are two strangers who meet on a train by accident - Guy is a professional tennis player and Bruno a huge fan. As the train continues on its journey, Bruno shares an idea he once had - two men who meet by chance swap murders. He then proposes a strange thing - if he disposes of Guy's unfaithful wife, Guy should murder Bruno's father in exchange. There's no connection between the two men and the police would never be able to connect them. Guy dismisses the theory as idle chit chat, but all that changes when his estranged wife is murdered.
- Robert Walker as Bruno Antony
- Farley Granger as Guy Haines
- Ruth Roman
- Patricia Hitchcock
- Leo G. Carroll
- Norma Varden
- Kasey Rogers as Miriam Haines (credited as Laura Elliott)
Robert Walker died five months after the films release, as a result of doctor's negligence. This was among the last (and by most accounts best) performances of his career.
As of 2011, Patricia Hitchcock is the last surviving member of the cast.
Patricia Hitchcock directed the sequence which contains her father's cameo.