California, 1869Abilene Carter and her older brother Todd, are suddenly orphaned on their western farm. After their parents funeral, they begin to work to take care of the family farm on their own. Abilene has a particularly hard time with the loss, visiting her parents lonely grave sites every day.On one summer day, when Abilene decides to go skinny dipping in a pretty sparse creek in a wooded area, Todd wonders along and finds himself mesmerized by the sight of his nude sister bathing. Over the next few days, an unusual cat and mouse game of incest begins as brother and sister flirt with each other and grow closer. In sexual frustration, Abilene shows off her nudable body to Todd, and both of them turn to auto-eroticism as the outlet for their passions. One night, Abilene, frightened by thunder from a storm, cries out. Todd rushes into her bedroom to see if anything is wrong and caresses his trembling sister. The caresses become more passionate and it leads to the two of them having sex.As the days go by, both Todd and Abilene begin to neglect their farm chores to pursue their passions for each other. Todd eventually realizes that what they are doing is wrong and he rides into a nearby town to console himself with liquor.In a nearby saloon, Todd confides his story to Linda, the floozy bar girl. (Note: Linda was first glimpsed during the opening credits being ravished by by the town ruffian Rawhide.) Rawhide overhears Todd's story and rides out to the farm. He breaks into the homestead where he rapes the defenseless Abilene. While at the same time back in town, Todd is having sex with Linda in her room.Todd returns home to the farm the next day and finds that Abilene has been raped. Todd rides back into town to find and kill Rawhide. Meanwhile, Linda goes to the farm to look for Todd and she finds a bruised and traumatized Abilene there instead and attempts to comfort her. Soon, both Linda and Abilene find a mutual sex attraction between the two of them and they both make love with each other.Todd arrives in town and challenges Rawhide to a gun duel, which evolves into a gunfight in which both men kill each other in the street outside the saloon.The final scene shows Abilene and Linda attending Todd's funeral who is buried next to his and Abilene's parents. Now all by themselves, Linda and Abilene, a committed couple, ride away in the family wagon for home to maintain the farm all by themselves.