Kyle Hanson is an emotionally bruised veteran of the Vietnam War who finds himself unable to rejoin mainstream society and lives as a drifter. While stopping in a small Southern town to eat, local bullies begin harassing him, a situation that culminates in a violent altercation with redneck Homer, after which Kyle flees. Relying on his special forces training, he manages to evade pursuing deputies. Kyle spends the night in a barn at the home of Jenny Bellows, a young mother whose husband went missing-in-action in Vietnam, and is presumed dead. Jenny now resides with her son, Bobby, and father-in-law, Sam Bellows, the richest man in town. In the morning, after Sam leaves on a business trip, Jenny encounters Kyle, who walks into the home uninvited. Having heard of the altercation the day before and the rumor that he is dangerous, Jenny is initially frightened, but soon finds herself sympathetic to Kyle.
Sheriff Jethro Pough learns that Kyle was previously incarcerated in a military psychiatric hospital during his service, and was catatonic for over a year. Meanwhile, several local men plan to hunt Kyle and eject him from the community, led by the imperious Deputy Dave. After evading several townspeople by fleeing into the woods, Kyle rejoins Jenny, and the two ride motorcycles together. She invites him into her home, and offers to wash his clothes and allow him to bathe. Meanwhile, a number of townsmen and local law enforcement stalk the house, having trailed Kyle there. Kyle manages to thwart their attempt at capturing him by causing their cars to explode and stealing a truck. Following a high-speed chase, Kyle crashes the truck into a river but escapes, leading the townsmen to believe he is dead until they are unable to find his body.
Kyle returns to Jenny’s home, where she reveals to him that Sheriff Pough has just informed her that her husband has been confirmed as deceased by the military. Later that night, Kyle accompanies Jenny and Bobby to the local fair, where they spend the evening at the carnival. Cece, a local farmer, spots Kyle with Jenny and calls Deputy Dave. The two men assail him at the carnival and kidnap him while Jenny takes Bobby to the bathroom. The men bring him to Homer’s farm, where they hold him hostage in a grain elevator. Locked in a cage, Kyle suffers posttraumatic stress disorder flashbacks to his time in Vietnam. The following morning, Deputy Dave brings a large gathering of men to the grain elevator to harass and beat Kyle. They attempt to wage a fight with him, but Kyle beats several of the men up before leaping from the top of the grain elevator into a river below.
The townsmen attempt to find Kyle in the water, but he hides beneath the surface to evade them. He steals a boat and is swiftly pursued by the men, who race after him in two others. Meanwhile, Jenny hears gunfire from the river, and picks up Sam and Sheriff Pough from her house to bring them to the scene. Using liquor bottles found in his boat, Kyle fashions molotov cocktails, which he hurls at his attackers from the shore, causing their boats to explode and leaving them stranded on a small island in the river.
Kyle is pursued on the island by the men, though Cece is now fearful of him. Kyle camouflages himself with mud and terrorizes his attackers with a number of traps and makeshift weapons, instilling fear in all of them. Jenny, Sam, and Sheriff Pough descend upon the scene as all of Kyle’s attackers flee fearfully into the river. Sam, having been informed by Jenny that Kyle is harmless, declares that Kyle may stay on the river island and have it as his own. Jenny looks on fondly as Kyle washes the mud from himself in the water.