Jack Ryan (Ryan O’Neal) is a Vietnam veteran with a criminal record who is employed as a migrant laborer on a California produce farm. When Camacho, one of his Mexican coworkers, tries to knife him during a softball game, Jack hits him in the face with a baseball bat. Jack is thrown in jail, but sprung out by the unscrupulous owner of the farm, Ray Ritchie (James Daly) and his head foreman, Bob Rodgers (Robert Webber) because they need to get the crop in on time and want no trouble with the police and the workers. However, they fire Jack, and Rodgers advises Jack to get out of town because otherwise, Camacho will surely come looking for him once he is out of the hospital.
En route to the migrant camp to collect his gear, Jack meets the beautiful Nancy Barker (Leigh Taylor-Young, then O’Neal’s wife), the secretary and mistress to Mr. Ritchie. Sam Mirakian (Van Heflin), a local justice of the peace who has taken a liking to Jack, offers him a job as a handyman. Jack accepts the offer, a decision that earns him Rodgers’ anger. Meanwhile, the volatile and scheming Nancy is bored by her current lot in life and wishes to move on. She tries to seduce Rodgers, but when Jack stands up to him, his defiance impresses her and she sets her sights on Jack instead.
Jack has a one-night stand with a divorcee and single mother Joanne (Lee Grant) who is staying at the motel in which Jack works. Joanne wishes their relationship to develop, but Jack stalls her since he has his eye on Nancy now. Nancy and Jack have several nighttime escapades along the beach, where she displays her penchant for antisocial and disruptive behavior, such as vandalism and breaking and entering. They soon become lovers. When Mr. Ritchie asks Nancy to sleep with a senator, presumably in exchange for some favor to his business, Nancy decides that she has had it and sets the next part of her plan in motion.
Nancy asks Jack to help her rob Ritchie’s safe in his house, which allegedly has more than $50,000 of payroll money for the Mexican migrant workers. That night, when a couple of unruly men hassle Nancy, she spitefully runs them off the road, injuring them. Jack tells her that the heist is off since Rodgers has seen them both together and also because he has become distrustful of Nancy because of her erratic and unstable behavior. However, when Nancy threatens to go to the police and blame him for the accident (they were in the car together at that time), he reluctantly agrees to her plan to rob the house that night.
Jack returns to the motel to find that Joanne has committed suicide because of problems with her ex-husband and her current boyfriend. Jack comforts her daughter, Cheryl.
That night, Nancy waits for Jack to come over. When she sees someone come in, she pulls out a concealed gun and shoots him dead. The intruder turns out to be Camacho, who had come in to settle scores with Jack. When Jack comes in, sees the situation, and questions Nancy, he correctly deduces that she intended to murder him simply because she thought it would be fun. Nancy decides to pretend to the police that Camacho intended to harm her and so she shot him in self-defence. To strengthen her version of events, she goes on a destructive spree through the house.
Nancy ends up being exonerated for her crimes in Mirakian’s court, presumably because of her story as well as the fact that she is a minor. Jack decides to leave town. While hitchhiking on the highway, he comes across Nancy, who offers him a lift. Jack refuses, saying that since it is a nice day, he prefers to walk.