Warren Beatty portrays Berry-Berry Willart, a hedonistic drifter in his 20s who has no trouble living off the women of all ages he seduces. When the women become too attached to him, his charm turns sadistic and frequently lands him in jail for battery. Berry-Berry is always on the road, far from home, rarely seen by his drunken father Karl Malden as Ralph Willart, his mother Angela Lansbury as Annabel Willart, or his sixteen-year-old brother Clinton Willart [Brandon De Wilde].
Clinton idolizes Berry-Berry, despite having to bail him out of jail in Florida, and later accompany Ralph to Western Union to wire bail money when Berry-Berry is arrested a second time for beating up a woman. Ralph’s remarks indicate this isn’t the first time he has wired bail money for Berry-Berry.
Eva Marie Saint as Echo O'Brien arrives, the 31-year-old daughter of a family friend who stays with them when she visits town. Echo has never married and is slowly getting over the suicide of her troubled long-time boyfriend. She is friendly toward the much younger Clinton, referring to him affectionately as "my guy."
But when Echo meets Berry-Berry, there is an instant mutual attraction between them, and they leave a family backyard cookout to be alone together. Berry-Berry asks Clinton for permission to be with Echo, saying that he wants her and she wants him, but acknowledging that Clinton saw her first. He says he will back off if Clinton does not give the okay. Clinton, knowing he has no real chance with Echo, tells Berry-Berry to treat her nice.
After this, Berry-Berry and Echo are constantly in each other’s company. When they return home after an evening out some time later, Echo learns she is pregnant. She tells Berry-Berry that she does not expect anything from him, that she took a gamble that someday he would love her, not that he would marry her—and she lost. As she explains, he is free, and Echo’s words leave him shaken in the rain. Clinton, who has been eavesdropping, witnesses the whole exchange.
Echo decides she must leave the Willarts’ house. She reassures Clinton, who is worried about the rain and the late hour, that she loves driving at night. But a later call from a state trooper reports that Echo drove off the road and was killed in the crash.
Ralph tells Annabel and Clinton that Echo was too good a driver for that crash to have been an accident, and that Berry-Berry must have had something to do with it. Clinton throws Berry-Berry’s framed portrait to the floor and stomps on it. Annabel pushes him away, picks up the portrait and clings to it, shrieking that she does not care what Berry-Berry’s done—she will love him always.
Clinton quietly slips into the shack where Berry-Berry has been living, retrieves the pistol his brother had shown him during a previous visit, and waits behind a curtain for Berry-Berry to return. When he does, Berry-Berry collapses sobbing onto the bed, having learned of Echo. Clinton puts the pistol back and leaves, seeing the brother he once wanted to emulate as someone to be pitied.
