Sylvie Cooper is a troubled teenage student at an expensive private school. She meets and befriends a poor
street-smart girl whose name she does not know. When a dog is hit by a car, the girl
kills it by striking it with a metal bar. Sylvie gives the girl the nickname "
Ivy" after seeing a stick-on tattoo of the plant she has on her thigh. Sylvie's father Darryl, against whom she is rebelling and with whom she frequently feuds, picks her up from school one day; Ivy asks for a ride. Ivy sits in the front with him and flirtatiously uncrosses her legs. Sylvie later confides in Ivy that Darryl is not her biological father and that she once tried to die by suicide. A few days later, Sylvie invites Ivy to her house, and Ivy wins the affection of Georgie, Sylvie's chronically ill mother. Soon after, as both of Sylvie's parents enjoy Ivy's company, Ivy practically moves in. The girls share clothes and Sylvie's bed, and, as they have similar figures, Georgie lends Ivy some of her clothes. However, Ivy starts inappropriately flirting with Darryl, as well as manipulating Sylvie into getting a permanent tattoo. Ivy also deduces that Sylvie lied about her suicide attempt and about Darryl not being her biological father. Darryl throws a party at the house to improve his failing career, and enlists Sylvie to help him. Ivy is able to manipulate the situation so that Sylvie is forced to leave the house while she remains to help. Ivy dresses seductively during the party and coerces Darryl, a recovering
alcoholic, into drinking
champagne. He embraces her but is caught by Georgie. Ivy apologizes, claiming that Darryl was under stress and she was merely comforting him. Georgie believes her, accepts a glass of champagne drugged with sleeping pills, and falls asleep. In the bed while Georgie sleeps, Ivy coaxes Darryl into performing
oral sex on her. Sylvie becomes increasingly irritated with Ivy's growing presence in her family. Her anger reaches a breaking point when even her dog chooses Ivy over her. Sylvie storms off and skips school to spend some time alone. Darryl picks up Ivy and drives them into the forest, where they drink and have sex. The next morning, Georgie walks onto her balcony. Ivy walks up behind her and without warning, pushes her off the balcony to her death. As Georgie was known to be gravely ill and had previously threatened to end her life, Ivy is not suspected. A few weeks later, Ivy convinces Sylvie to take her out for a joy ride in Georgie's old sports car. When Sylvie becomes suspicious of her involvement in Georgie's death, Ivy crashes the car, then moves the unconscious Sylvie into the driver's seat to make it appear that she was the one driving. In the hospital, Sylvie hallucinates that her mother visits her, and sneaks out to return home, continuing to have hallucinations of her mother on the way. Once inside, she sees Darryl and Ivy having
sex, and flees in horror. Ivy inadvertently lets it slip that she was driving during the accident, causing Darryl to realize that everything she has said has been a lie. He leaves to find Sylvie. Ivy goes upstairs to Georgie's old room and stands in the balcony. Sylvie approaches from behind, deliriously seeing Ivy as her dead mother. When Ivy kisses her in a suggestive manner, it breaks her out of the delusion. After a brief scuffle, Sylvie pushes Ivy off the balcony to her death. Ambiguously, Sylvie narrates that she still loves and misses "her". ==Cast==