Cattlemen and sheepmen are in dispute over grazing rights on the range. Bronco doesn't want to get involved but has to step in before a range war breaks out, mainly because the sheepmen are Quakers who refuse to carry guns and the cattlemen have no such qualms.
Pursued by Marshall Gaffney for a robbery he did not commit, Bronco rides to the town of "Last Resort" -- a hideout for outlaws on the Mexican border run by Three Fingers Jack. There Bronco hopes to clear his name by finding the real robber -- a charming but treacherous man named Billy Styles.
Bronco hires a mother and son who are refugees from the fallen empire of Emperior Maximilian of Mexico, but he soon discovers that bandits who believe the two know where $5 million in gold is buried are after them.
Bronco gets involved in a range war and is helped by outlaw Billy the Kid. However, after everything is settled, Billy still remains a wanted outlaw and is being pursued by bounty hunter Pat Garrett. Bronco wins a range war with the help of Billy the Kid, but when the dust settles the outlaw is still wanted by the law and by bounty-hunter Pat Garrett.
Bronically is finally able to convince an army officer to send the Osage Indians to a fertile reservation in Wyoming, but an epidemic of cholera and a hostile new commander may both torpedo his efforts.