On orders from Governor Gosper, Wyatt Earp heads south when he learns that Old Man Clanton has sent his men into Mexico to steal the cattle of a wealthy rancher and rob the silver trains.
Ranch hand Mitch Hallam becomes Earp's newest deputy, seeking to prove his worth and earn the hand of his boss' daughter. He puts his job and his life on the line when he reveals an underhanded scheme being perpetrated by the other workers.
Wyatt arrests the McLowery brothers, only to watch Sheriff Behan sheriff let them go right after, at the direction of Old Man Clanton.
Old Man Clanton's idea of a perfect son-in-law is Wyatt.
Wyatt recalls the details of the day the Clanton gang rode into Tombstone to shoot it out with the Earps; he initially plans to avoid a street shoot-out by arresting the gang members separately.