Joe Branch, reputed to be the son of Jesse James, comes riding into Coffeyville Kansas, looking for proof one way or the other regarding the question of who his father was.
The notorious Dalton Boys have decided to go straight and move to Argentina. Just before they leave, they learn of a friend whose land is about to be seized by a greedy land company. Before they can help, the man is killed by a company assassin. The brothers do manage to rescue his widow and head for the hills. There, they decide to revert back to outlaw life. Meanwhile, a newspaper publisher's daughter falls for one of the brothers.
Deputy Marshall Larry West goes undercover to find out who has been terrorizing the territory, Navajos or the Dalton Gang.
The story of one of the notorious members of the infamous Dalton Brothers outlaw gang.