When Billy Blue Cannon is forced into a showdown with wanted gunfighters, he is saved by a wandering dentist who proves to be fast with a gun. John Cannon returns the favor to Doc Henry by agreeing to send Billy Blue to help the dentist establish a practice in Tucson.

Billy Blue is kidnapped en route and held for ransom by the gunfighters, Jacques Dubois and Kid Curry. The boy loses faith in his new friend when the dentist throws in with the crooks. John Cannon corners Doc Henry with the ransom and prepares for a shoot-out.

Buck and Manolito invade the Apache stronghold to rescuer a captive white girl.

Ann, an Apache slave for five years, is rescued by Buck and Manolito as she flees from her captors, but her frail sister Olive is recaptured. John asks a passing Army detachment for aid, but the unit is massacred before it can help. Buck and Manolito ride unarmed into the Apache stronghold prepared to buy the girl's freedom, but the Apache chief and the medicine man offer to let them go free with the girl if Manolito can survive a test of courage.

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.

Ramon Novarro, silent film notable is guest star as Padre Guillermo, who flees Mexico to escape the vendetta of a twisted killer.

The padre is accompanied by two nuns and Maria. John Cannon agrees to protect the group when Maria's demented fiancé Ramon, who has plundered the padre's Mexican convent, arrives on the scene. Maria rides into the desert intent on sacrificing herself to prevent more bloodshed. Manolito finds Maria, but is trapped with the girl by Ramon.