In early winter, a man arrives at a run-down Georgian house in a smart terrace in London's Chelsea district. He is Barrett, who has come to be interviewed for the job of manservant. His prospective employer, Tony, is newly-returned from Africa and has just bought the house. He is enjoying a post-lunch nap in the kitchen when Barrett arrives.
Barrett is smartly turned-out, properly deferential, and has a northern accent. Tony is rich and upper-class, with blond, rather effeminate, good looks. He has an upper-class girlfriend, Susan, and a job lined up, building new cities in Brazil. Barrett relates his experience, and Tony hires him.
The two men set about planning the refurbishment of the house and Susan calls, to see the improvements. Tony asks her to marry him. One evening, Barrett interrupts their lovemaking in the drawing room. When Tony catches a chill and is confined to bed, Susan argues with Barrett about the presence of flowers in the room.
Barrett tells Tony there is too much work for him to do alone, and suggests they hire a maid. He rings his sister, Vera, in Bolton and asks her to come to London. Susan tells Tony of her dislike and distrust of Barrett. While they are enjoying a meal in a local trendy restaurant, Barrett meets Vera at Kings Cross station and takes her to Chelsea. He introduces her into the household as the new maid. She is young and sexy, and Tony is attracted to her.
Tony visits Susan's family in the country. They are rich but stupid people. Back at the house, Barrett appears to be having sex with his 'sister'.
One day Barrett casually draws Tony's attention to the shortness of Vera's skirts, in a censorious, 'brotherly' fashion, and then Tony surprises her in his bathroom. Bothered and bewildered, Tony goes out, and Barrett and Vera take a bath together, laughing at him behind his back.
Barrett announces that their mother is sick and he and Vera leave for the station to visit her in Manchester. Vera comes back, saying she didn't feel well enough to travel. Left alone in the house, Vera seduces Tony.
Susan arrives unannounced at the house one morning when Tony is out. She starts to order Barrett about, imposing herself on the household and humiliating him. She questions what he really wants.
Back at her family home, Susan and Tony seem to be happy, and decide to return to the London house early. They discover Vera and Barrett in bed together in Tony's room. Tony and Barrett argue, and Barrett says that Vera is his fiancée, and not his sister. Susan realises that Tony has slept with Vera. Tony orders Vera and Barrett out of the house. They leave noisily, while Tony drowns his sorrows in drink. Susan leaves in disgust.
Alone in the house, Tony sinks into a torpor, while the mess builds up around him. He longs for Vera. One evening, he runs into Barrett again in a pub. Barrett is full of remorse and begs to be taken back into the house. Tony agrees, but this time the relationship has changed - Barrett is now the dominant personality in the household. He claims that Vera has left him for another man.
Tony is drinking more and more heavily. The master-servant relationship has completely disappeared, and Barrett behaves as he pleases, treating Tony as his social equal. They begin to play strange games.
Vera reappears. Barrett dangles her in front of Tony, before whisking her away again. He starts to procure exotic liquors and then women for Tony, who is now in an almost permanent drunken stupor.
Susan turns up on one of these evenings, and Barrett takes his revenge by treating her like one of the prostitutes he has invited round. Just as an orgy gets under way, orchestrated by Barrett, he suddenly orders everyone to leave, including Susan. Susan strikes Barrett in the face as she goes out into the street, where she collapses in a fit of weeping. Tony is unconscious on the floor. Only Barrett and Vera remain.
