In 1868, Ethan Edwards returns after an eight-year absence to the home of his brother Aaron in West Texas. Ethan fought in the Civil War on the side of the Confederacy, and in the three years since that war ended, he apparently fought in the Mexican revolutionary war, as well. He has a large quantity of gold coins of uncertain origin in his possession, and a medal from the Mexican campaign that he gives to his eight-year-old niece, Debbie. As a former Confederate soldier, he is asked to take an oath of allegiance to the Texas Rangers; he refuses.

Shortly after Ethan's arrival, cattle belonging to his neighbor Lars Jorgensen are stolen, and Rev. Captain Samuel Clayton leads Ethan and a group of Rangers to recover them. After discovering that the theft was a Comanche ploy to draw the men away from their families, they return and find the Edwards homestead in flames. Aaron, his wife Martha, and their son Ben are dead, and Debbie and her older sister Lucy have been abducted.

After a brief funeral, the men set out in pursuit. They come upon a burial ground of Comanches who were killed during the raid. When they find the Comanche camp, Ethan recommends a frontal attack, but Clayton insists on a stealth approach to avoid killing the hostages. The camp is deserted, and further along the trail, the men ride into an ambush. Despite fending off the attack, the Rangers are left with too few men to fight the Native Americans effectively. They return home, leaving Ethan to continue his search for the girls with only Lucy's fiancé, Brad Jorgensen, and Debbie's adopted brother, Martin Pawley. Ethan finds Lucy brutally murdered and presumably raped in a canyon near the Comanche camp. In a blind rage, Brad rides directly into the camp and is killed.