When a wagon team headed by John Ames (William Duncan),loaded with gold and heading for California, is ambushed by Lee Tate (Charles Bickford) and his renegades, only Dick Ames (Gene Reynolds) and Bob Ames (Billy Lee), John's two young sons escape. Bob is taken away by Tate, who brings him up as his own son. Dick, left for dead, witnesses the massacre, and is later found by Rafael Lopez (J. Carroll Naish), a Mexican prospector. Years later, Dick (Gilbert Roland), now known as "Arizona", and Lopez ride into a small town where Tate and his men are running things their own way. He is engaged in stealing a gold mine owned by Jim Morgan (Barlowe Borland) and his daughter Amy (Marsga Hunt), when "Arizona" recognizes him as the man that led the massacre years before. He is trying to find proof of Tate's guilt when he is confronted by Bob (James Craig), who starts a fight with him. "Arizona", during the fight, recognizes Bob as his brother by an old scar. Bob joins "Arizona" in his fight against Tate, and together they rid the town of Tate and his gang.