Martha Edwards opens the door of her cabin to the arid Texas landscape outside just as her brother-in-law, Ethan Edwards, approaches on horseback. Although it is 1868, Martha, her husband Aaron, their children Debbie, Lucy and Ben, and their adopted son, Martin Pawley, have not seen Ethan since he left them to fight for the Confederacy during the Civil War. Because Martin, an earnest but friendly young man, is part Cherokee, Ethan treats him coldly, even though it was he who rescued the lad when his parents were massacred in an Indian raid years earlier. Soon after Ethan's arrival, Rev. Samuel Johnson Clayton, a captain in the Texas Rangers as well as an old family friend, announces that the cattle of local rancher Lars Jorgensen have been stolen. Although Ethan is somewhat contemptuous of Sam, he joins Martin and a posse in pursuit of the thieves. When they find that the bulls have been killed with Comanche lances, Ethan declares that what the Indians really wanted was to lure the men away from home, thereby leaving their ranches open to attack. The men head back, but it is too late, for upon their arrival at the Edwards home, they discover that everyone has been brutally murdered except for Lucy and Debbie, who have been taken by the Comanche. The posse then sets out to find the girls. On finding a fresh Comanche grave, the men unearth the body but are shocked when Ethan shoots out its eyes. According to Comanche belief, Ethan explains, this will prevent the dead man's spirit from entering the spirit lands and force him to wander forever. The next day, the Comanche raiding party, led by Chief Scar, surrounds and attacks the posse, but the rangers drive them off. When Sam refuses to pursue the Comanche, explaining that they should be allowed to bury their dead in peace, Ethan explodes, and storms away from the men, intending to continue the search on his own. Both Martin, who endures Ethan's insults for the sake of his missing sisters, and young Brad Jorgensen, who loves Lucy, insist on joining him. One day, Brad returns from a scouting mission and joyfully announces that he has seen Lucy's blue dress at a nearby Indian encampment. Ethan reveals that he found Lucy's body and covered it, then angrily warns Brad never to ask him to reveal more. Wild with grief, Brad rides into the Indian camp and is shot to death while Ethan and Martin look on in horror. One year later, Ethan and Martin visit the Jorgensen ranch, and Ethan admits to Lars that they have lost the war party's trail. Lars replies that a Texas merchant named Futterman claims to have knowledge of Debbie's whereabouts. Meanwhile, Martin confides in Lars's daughter Laurie, who is in love with the young man, his fears that Ethan may kill Debbie because of her long association with the Comanche. To Laurie's dismay, Martin then leaves to follow Ethan, who has departed without a word. The two give Futterman money in exchange for the news that Debbie is held captive by Scar. That night, Futterman tries to shoot Martin and Ethan, but Ethan kills him and his henchmen, then retrieves his money. Time passes, and Laurie, who is now being courted by the bumbling Charlie McCorry, receives her only letter from Martin. In it, he confesses that he inadvertently "bought" a squaw he named Look, who trembled when he asked her about Scar, but left him an arrow fashioned of rocks before leaving him during the night. Later, Martin and Ethan discover that Look joined the Comanche but was killed when the band was raided by the U.S. Cavalry. Ethan and Martin examine the prisoners taken during the raid, but do not find Debbie among the several white women found living with the Indians. His voice tinged with loathing, Ethan watches the women and remarks, "They ain't white anymore. They're Comanche." In a New Mexico cantina, the two searchers meet Mose Harper, a dull-witted but loyal old friend who, in exchange for the promise of a comfortable rocking chair, introduces them to Mexican Emilio Figueroa, who claims to know Scar. Emilio takes them to Scar's village, where they finally meet their elusive enemy, who explains that because his two sons were killed by white men, he has taken many white scalps in revenge. One of his wives, a young white woman, then displays some of the scalps on a pole. Later that day, Ethan and Martin are visited by the woman, who, although admitting she is Debbie, begs them to leave and states that the Comanche are now her people. Disgusted that Debbie has been "living with a buck," Ethan aims his gun at her, but Martin steps between them. At that moment, Scar attacks, and while Debbie runs back to the Indians, Ethan and Martin escape. Ethan eventually recovers from a gunshot wound received during the encounter, and the two return to the Jorgensen ranch, just as Laurie and Charlie are about to exchange marriage vows. Laurie is thrilled at the return of the man she really loves, but Charlie is angry and challenges Martin to a fight. The altercation ends amicably, and Charlie calls off the wedding. Clayton, who was planning to marry the couple, assumes his role as the local lawman and arrests Martin and Ethan for the apparent murder of Futterman. Just then, cavalry lieutenant Greenhill arrives with orders from Col. Greenhill, the flustered young officer's father. The rangers are to join the colonel in the field for a "joint punitive action" against the Comanche. Greenhill brings in Mose, who has been held captive by Scar. Injured and shaken, Mose reveals Scar's location, whereupon the men immediately prepare for a surprise attack. Worried that Debbie will be killed in the coming battle, Martin sneaks into Scar's camp to rescue her, even after Ethan reveals that one of the scalps on Scar's pole belonged to Martin's mother. When Martin enters Debbie's tent, she screams but admits that she wants to leave. When Scar appears, Martin shoots him, and Sam and the rangers attack the camp. Ethan finds Scar's lifeless body and scalps it, after which he begins to chase the frantic Debbie. As the battle rages around them, Martin tries to stop Ethan, but Ethan catches Debbie and, instead of killing her, suddenly lifts her into the air, tenderly cradles her in his arms and says, "Let's go home, Debbie." Sam and his rangers win the battle, after which everyone returns home. Ethan delivers Debbie to Mrs. Jorgensen's tearful embrace, and Laurie joyfully greets Martin, while Mose, looking on from his rocking chair, smiles. Ethan surveys the scene from the door of the house, turns around and slowly walks away.