The proposal that Guy, a successful tennis player, receives on the train while talking to an unknown fellow passenger is already beyond bizarre, but then Guy’s unfaithful wife is murdered almost immediately afterward, proving that the stranger meant exactly what he said. Indeed, that man, Bruno, suggested they each “relieve” the other of someone inconvenient, thereby confusing the police as to motive. Now it’s Guy’s turn: He’s to kill Bruno’s hated father… The picture follows the protagonists’ actions in parallel, and the growing suspense is amplified by the fact that the viewer knows what psychopathic Bruno will do next, before desperate Guy does. The thriller noir atmosphere and expressionist inspiration particularly emanate in the amusement park scenes; and the reflection of the murder in the strangulation victim’s glasses is a telltale sign of Hitchcock’s authorship.