Sarah Morton, a middle-aged English mystery author based in London, who has written a successful series of detective novels, is experiencing
writer's block that is impeding her next book. Her publisher, John Bosload, offers her his country house near
Lacoste, France, for some rest and relaxation. Sarah takes him up on the offer, hinting that she hopes John may visit. After settling into the spacious, sun-filled house and meeting the groundskeeper, Marcel, Sarah finds her quietude disrupted by a young woman claiming to be John's daughter, Julie. She arrives late one night explaining that she is taking time off from work herself. She eventually tells Sarah that her mother used to be John's mistress, but that he would not leave his family. Julie's sex life consists of
one-night stands with various men, and a competition of personalities develops between the two women. At first, Sarah regards Julie as a distraction from her writing. She uses earplugs to sleep during Julie's noisy sexual encounters, but develops a voyeuristic fascination with them, abandoning the earplugs during one of Julie's trysts. Sarah sneaks into Julie's room and steals her diary, using it in the novel she is working on. The competition comes to the fore when a local waiter, Franck, is involved. Julie is attracted to him, but he appears to prefer the more mature Sarah, having struck up a relationship with her during her frequent lunches at the bistro. An unexpected tragedy occurs after a night of flirting among the three. After swimming together in the pool, Franck refuses to allow Julie to continue performing oral sex on him once Sarah, who is watching them from the balcony, throws a rock into the water. Franck tells Julie he is leaving. The next day, Franck is missing. While investigating Franck's disappearance, Sarah is told that Julie's mother died years earlier, though Julie had spoken of her mother as if she were alive. She returns to the villa, where a confused Julie thinks Sarah is her mother and has a breakdown. Julie eventually recovers and confesses that Franck is dead after she repeatedly hit him over the head with a rock as he tried to leave her at the pool. His body is in one of the sheds. When Marcel becomes suspicious of the mound of fresh soil where Sarah and Julie have buried Franck's body, Sarah seduces him to distract him. Julie leaves, thanking Sarah for her help and leaving her the manuscript of an unpublished novel she claims her mother wrote, which she had previously said John made her mother burn. Sarah uses the mother's manuscript in her novel. Sarah returns to London and visits John at his publishing office with her new novel, titled
Swimming Pool, which she anticipated he would reject, so she had it printed by another publisher. His daughter, Julia, arrives just as Sarah is leaving, but is revealed to be a different person from the girl who came to John's house in France. == Cast ==