A young, sexually promiscuous woman who arrives at the country house claiming to be the publisher's daughter. She engages in a psychological and romantic rivalry with Sarah. After killing Franck with a rock during a pool confrontation, she confesses to Sarah, suffers a mental breakdown, and leaves her late mother's unpublished manuscript behind.
Their rivalry drives the film's psychological tension.
A competition of personalities develops between Sarah and Julie, especially around Franck and the country house.
Their sexual relationship becomes possessive and ultimately violent.
Julie is attracted to Franck, and the two engage in sexual activity by the pool.
His suspicion also places pressure on Julie's secret.
Marcel notices the fresh mound created after Sarah and Julie secretly bury Franck's body.
Julie presents herself as John's illegitimate daughter, although her identity is later complicated.
Julie arrives at the country house claiming to be John's daughter and later says her mother was once John's mistress.
The film distinguishes Julie from John's actual daughter Julia.
The ending explicitly reveals that the girl at John's office, Julia, is different from the girl who came to the country house.
Explore the full interactive character relationship map of Swimming Pool