Twisted Nerve is a 1968 British psychological thriller film directed by Roy Boulting and starring Hywel Bennett, Hayley Mills, Billie Whitelaw and Frank Finlay. The film follows a disturbed young man, Martin, who pretends, under the name of Georgie, to be intellectually impaired in order to be near Susan, a girl with whom he has become infatuated. Martin kills those who get in his way.

Martin plays catch with his older brother Pete, who has learning difficulties and has been sent to live in a special boarding school in London, by their mother. Martin is the only remaining figure in Pete's family life; their father died years before and their mother has a new life with her new husband, a wealthy banker. The school's physician believes that Pete cannot be expected to live much longer.

In a shop, Martin sees Susan purchase a toy. As she leaves, Martin follows after having pocketed a toy duck. Two store detectives ask them to return to the manager's office. The detectives assert that Martin and Susan were working together to steal the toy. Susan says she has never met Martin.

When questioned by the manager, Martin presents himself as mentally challenged, and calls himself "Georgie". Now disbelieving in a link between them, the manager asks Susan for her address, and Martin makes a mental note when she offers it. Sympathetic to him, Susan pays for Martin's toy.

Martin returns home and finds his parents arguing in the parlour, over his lack of interest in life, his unusual behaviour and the duck incident. In his room, now behaving as "Georgie", he rocks in a rocking chair while smiling in the mirror and caressing a stuffed animal. The rocking motion of the chair is smashing a photo of his stepfather.

The next day, Susan goes to the library, where she keeps an after-school job. Martin approaches Susan, who recognises him as Georgie. Martin says that he followed her, and pays her back for the toy. Before leaving, Martin gets Susan to lend him The Jungle Book.

Martin has a dispute with his stepfather, who insists he travel to Australia. Martin refuses and returns to his room. Martin stares in the mirror, bare-chested, and caresses himself. He then removes the rest of his clothes. There are male bodybuilding magazines on his dresser. A frustrated Martin eventually smashes the mirror.

Martin sets in motion a plan to leave home, pretending to go to France. He then shows up at Susan's mother's house, where she rents rooms. Presenting himself as Georgie, he gains sympathy both from Susan and her mother, who let him stay. Martin wants Susan to accept him as a lover, but cannot reveal that he is in fact Martin, as he is worried she will shun him.