Pima Indians are attacking and killing Apaches in the area. Blue and Buck find two orphaned Apache boys that trail them back to the High Chaparral and morph into ten Apache kids. One is the grandson of Geronimo putting the ranch in danger.
The Tenth Cavalry comes to Tucson to stop crime. They are Buffalo Soldiers who must also contend with racism. With aid from the Cannons they show their pride and great ability as they take on the man controlling the town and his henchmen.
Blue kills a soldier attacking an Indian girl and takes the body to the fort only to learn he is the son of a general who wants justice for his dead son. Big John tries to defend his son in the court martial but he is out of his element.
Sam receives a letter causing him to return home to kill a man who is also a good friend. The men learn from San and his brother Joe that Sam has a wife and daughter. Worried the men decide to follow to support Sam's quest for revenge.
An Army shipment of rifles is stolen by Apaches. Blue is taken captive by the Chief Morales until Big John proves the Apaches were not involved in the attack. Manolito locates the real culprits but no one knows it or his location.
Buck and Manolito come upon two white girls being chased by Apaches. They are able to save the older girl but her sister is retaken by the Apaches. Buck promises they will attempt to save her sister but everyone knows it is not feasible.
The men deliver a herd and celebrate in the local town. The town is rough and Blue has the misfortune to draw the ire of a professional gunman. Blue decides he must stay in town and face the man against the wishes of his dad and the men.
Victoria is injured when a prisoner, a doctor being held for murder by a marshal, tries to escape. Big John is left with no choice but to have the prisoner operate on her. He has to go against the marshal who believes Victoria will die.
A dentist rescues Blue from Apaches and bandits. With no money to be made at the ranch, he decides to go after the bandits who have a $1000 bounty on them. When the bandits kidnap him and Blue, he tries to take advantage of it.
Buck finds two wandering Apache boys chasing a steer. He gets Big John's approval to train them as cowhands. Skeptical locals assume they killed a rancher. After some hands are killed, the missing boys are assumed to be involved.