When Mangas Colorado and his band of Apaches raid a camp of Mexican bandits who have stolen their horses, they retrieve their property and also take Riva, a half-Mexican, half-Comanche Indian girl whose father was killed by the horse thieves during a raid on his ranch. Mangas, pulling Riva along by a leash, and his band visit the camp of trader Luke Fargo, Mangas' old friend. When Judge Bolton, who is in the area to make a peace treaty with the Apaches, asks about the girl, Fargo explains that the Apaches kidnap Mexican girls to sell to white saloon owners. The judge is disgusted at the Indians' blatant practice of white slavery, but Fargo compares their actions to the U.S. government's placing of Indians on reservations as well as to the Southern states' legalized slavery. Around the campfire Riva sings and dances with Fargo, and smitten, he offers to trade guns for the girl, but Mangas refuses. The Apaches return to their village, where Mangas announces that he wishes to make Riva his wife. The Apaches, including Mangas' best friend Ponce, are distressed, and medicine man Chino says that the spirits will retaliate if Mangas marries outside of Apache custom. Although Ponce changes his position, two other warriors challenge Mangas, who fights them to the death. Mangas' cousin Yellow Moon and his sister Nona do not easily accept Riva, and when they attempt to force her to do squaw's labor, including building a wicky for her husband-to-be, Riva brawls with them and then tells Mangas that she will be treated as his equal. Mangas agrees, and then teaches Riva to shoot and hunt. At the wedding ceremony, Fargo, disappointed that he has lost Riva, nonetheless offers her a horse as a wedding present, and on the couple's wedding night, Riva teaches Mangas to kiss like an American. Later on, gold miners violate the American peace treaty by panning in Apache territory, and when Nona confronts them, they beat her and then shoot and injure her son, Little Owl. Mangas tries to convince the miners to go away peacefully, but they capture him and whip his backside, leaving humiliating scars. The enraged Apache chief then alerts Riva and the other warriors, and they raid the camp, killing all but one of the men. Later, Judge Bolton and Fargo meet at the site of the recent raid, and Sheriff Bullard announces his intent to teach the Apaches a lesson. Fargo asks that he may be permitted to go see Mangas to ascertain the truth, before they resort to violence. The judge agrees, but insists that the troops be shown the Apaches' hiding place. With the troops behind him, Fargo approaches the Apache band with a white flag, but as Mangas leaves his cover, Riva, spotting the troops assembled, cries out a warning. Ponce, in a panic, fires the first shot and kills Judge Bolton. During the ensuing battle, Fargo is wounded, and Riva nurses his wounds. When Mangas shows up, he recounts his humiliation at the hands of the miners, and Fargo says farewell. As the Apaches continue their raids on miners' camps, wagon trains and settlements, the Civil War breaks out, and Fargo becomes a U.S. Army major. Mangas is shot in a skirmish, and Riva, refusing to entrust her beloved husband to Chino, has him taken to a white settlement where an American doctor can treat him. After the doctor has finished tending Mangas' wounds, Fargo and his troops arrive at the settlement, and Fargo goes to see Riva and Mangas. Fargo explains that he has received orders to kill the Apache warriors and send the women and children to Fort Stanton, unless the Apaches put down their weapons and go peacefully to the reservations. Mangas refuses that option, but makes peace with his old friend Fargo. Fargo, realizing that Mangas will never give up, calls a temporary truce in order to allow the Apaches to seek refuge in the mountains. Riva, Mangas and their band of warriors depart with dignity.