After a band of Apaches massacres a wagon train of French Canadian nuns bound for Santa Fe, Sister Mary, the sole survivor, buries the dead and eventually meets up with gunslinger Madron. Impressed by her goodness, as well as by her ability to handle a gun, Madron accompanies her on the treacherous journey across the desert. Attacked by a group of Apaches led by Sam Red, Sister Mary frightens off the Indians and sews up Madron's wounds. To divert a band of outlaws, Madron tears off the front of Sister Mary's habit, then guns them down, Sister Mary wins over the survivor, Angel, by pointing a gun at him and Madron until they swear to become allies. As the trio makes its way across the desert Apaches follow. To mislead their pursuers Angel suddenly rides off. After another narrow escape from the Apaches, to comfort the distraught nun Madron makes love to her. The following morning, Sister Mary removes her coif and asks Madron to call her Antoinette. Learning of Angel's capture by the Apaches, Madron instructs Antoinette to continue to Santa Fe while he goes to Sam Red's camp to rescue their comrade. Seeing that Angel is being skinned alive, Madron shoots him to end his agony. The Apaches attack Madron, and he kills most of them, including Sam Red, before dying himself from a gunshot wound. Sister Mary hears the shots and realizes that Madron has sacrificed himself to save her, and she continues her journey.