In 1885, a small band of Apache Indians, led by Geronimo, are captured by U.S. Cavalry captain Case McCloud, who respects the Apache and Geronimo, in particular. At Fort Steele, Arizona, Geronimo signs a peace treaty on the understanding that the land he is to be given will be free of white men. When three white men, Benjamin Alsop, Cliff Taggert and Dan Avery, promote gold mining in the mountains on the Indians' land, Case closes them down. Case is romantically involved with Norma Clemson, who intends to open a school on the reservation so that Indians can have the same opportunities as anyone else and become useful citizens. Taggert and Avery attempt to bribe Case to permit mining on the reservation, but he throws them out. After anti-Indian political maneuvering in Washington results in Case being relieved of command, the miners resume operations and take Tubai, Geronimo's son, hostage and torture him. Case and several soldiers free Tubai. Maj. Nathan Stark, sent to replace Case, does not enforce the treaty for fear of censure by the citizens of nearby Tucson. Alsop and Taggert plan to murder a white man and make it appear to have been done by the Apaches so that warfare will erupt. Taggert kills an old miner, Sagebrush, with an Arapaho arrow and takes the body to the fort, where his gunmen kill Indians who have come there in peace. Case orders his soldiers to fire on Taggert and his men, and after several are killed, is arrested and relieved of duty. Geronimo attacks one of Stark's troops, trapping them. In the meantime, Case learns that Sagebrush was killed by an arrow from a distant tribe. After a young lieutenant allows Case to escape, he induces Avery to admit that Taggert has been in Arapaho country. Case then finds the bow and arrows in Alsop's office and takes him into the foothills. Taggert shoots Alsop, but Case beats him up and takes him to where the soldiers are pinned down. Case reports to Stark and offers to talk with Geronimo and explain how he has been tricked into war. After Taggert has confessed to Stark that he killed Sagebrush and Alsop, Case shows his signed confession to Geronimo and asks him to meet with Stark. Geronimo asks Stark to swear that a new treaty will be kept, but the major refuses to do so. After Cavalry reinforcements arrive from another fort, Geronimo is captured, and Stark reveals to Case that he was sent west specifically to accomplish this, and that Geronimo will be going to a prison in Florida. Later, Case resigns from the Army and goes to see Geronimo, who is being held at the fort. He offers the chief his sword and tells him that he feels great dishonor. After Geronimo tells him that he should keep his sword, that his people will honor it as the only one raised in their defense by the white man, Case decides to remain in the Army and plans to marry Norma.