Psychotic Bruno Anthony (Walker) and amateur tennis athlete Guy Haines (Granger) meet by chance aboard a train.

Both men discover each has someone they'd like out of their lives. So Bruno suggests he murder Guy's wife Miriam (Rogers), while Guy could reciprocate by offing Bruno's father.

But if Guy thinks he and Bruno were merely having some witty wordplay aboard the train, how wrong he is!

Their conversation turns out to be deadly real when Bruno kills Guy's wife...and now expects Guy to fulfill his end of the bargain.

With the police ready to finger Guy for the murder of his wife, can the poor man prove his innocence? Or will he be forced to seal the deal by killing Bruno's father?

Exceptional, well done suspense throughout. The superbly photographed death of Miriam - stylistically reflected through her eyeglasses - is ahead of its time and echoes later giallo-esque conventions.

Walker gives a standout performance as the disturbed Bruno.

A must see.