Deanie Loomis (played by Natalie Wood), a teen-aged girl living in a small town in Kansas in 1928, follows her mother's advice to resist her desire for sex with her boyfriend, Bud Stamper (Warren Beatty), the scion of the most prosperous family in town.

In his turn, Bud reluctantly follows the advice of his father Ace (Pat Hingle), who suggests that he find another kind of girl with whom to satisfy his sexual desires.Bud's parents are disappointed by, and ashamed of, his older sister Ginny (Barbara Loden)—who is sexually promiscuous, smokes, drinks, and has had an abortion—and accordingly "pin all their hopes" on Bud, pressuring him to attend Yale University.

Bud does find a girl who is willing to become sexually involved with him, and when Deanie finds out, she is driven close to madness and institutionalized. Bud's family loses its fortune in the Great Depression, which leads to the father's suicide; Ginny dies in an automobile accident; and Bud takes up ranching, which he had postponed because of his father's aspirations for him.

In the final scene, Deanie, home from the asylum after two and a half years, goes to meet Bud. He is now married to Angelina (Zohra Lampert), the daughter of Italian immigrants; he and his wife, whom he met while complying with his father's desire that he attend Yale, have an infant child and are expecting another one. After their brief reunion, Deanie and Bud see that they must continue their lives separately. (From Wikipedia)