Martin (Hywel Bennett) lives at home with his mother and stepfather, who is worried about his lack of motivation.
When he tries to send him to Australia to take a job, Martin says he’s going to Paris but goes to stay at the house of Susan (Hayley Mills), a young woman he met in a toy shop.
He pretends to have learning difficulties and they treat him like a child.
One night he sneaks out of the house and murders his stepfather.
Susan finds out who he really is and goes home to warn her mother (Billie Whitelaw), but Martin has already killed her.
Martin shoots himself and the police arrive to find him dying at Susan’s feet.
The movie reunited Bennett and Mills with director Roy Boulting who also directed the young artists in the The Family Way (1966).
Sir John Forrester