Having read all about Guy, Bruno is aware that the tennis player is trapped in an unhappy marriage to to wife Miriam (Laura Elliott) and has been seen in the company of senator's daughter Ann Morton (Ruth Roman). Baiting Guy, Bruno reveals that he feels trapped by his hated father (Jonathan Hale).
As Guy listens with detached amusement, Bruno discusses the theory of exchange murders. Suppose that Bruno were to murder Guy's wife, and Guy in exchange were to kill Bruno's father? With no known link between the two men, the police would be none the wiser, would they?
When he reaches his destination, Guy bids goodbye to Bruno, thinking nothing more of the affable but rather curious young man's homicidal theories. And then, Guy's wife turns up strangled to death.
Co-adapted by Raymond Chandler from a novel by Patricia Highsmith, Strangers on a Train perfectly exemplifies Hitchcock's favorite theme of the evil that lurks just below the surface of everyday life and ordinary men.