Billy Blue Cannon quits the ranch after a quarrel with his father and leads a peace representative of the President to Cochise. On the trail Blue falls in love with Kelly's adopted Apache daughter, Moonfire. Kelly, an idealistic dreamer, meets Cochise's demands for a strip of land separating the High Chaparral from Tucson. This would cut the Cannons' supply route and threaten them with bankruptcy. John, angered by the peace terms and his son's choice of a wife, prepares to defend the ranch against the Apaches.