Jake Worthy was not born to be a gunman. His sole shooting offence was firing back at a crooked gambler in a Tucson saloon. For that he received a six-month sentence in the notorious Yuma prison. He meant to serve out his time patiently until he could return to Rio Lobo and Becky Holland, the girl who waited for him there. Bushwhacked along the trail home, he was taken in by a gang of thieves who wanted him for his gun. Led by a beautiful, money-crazed woman named Yvonne and a cold-eyed killer, Bill Davenport, they meant to pull a big freight office job, but were short of gun hands. It was join up with the gang or be left in the mountains to die. Urged on by Yvonne, Jake was led along a trail of treachery, violence and murder which destroyed his chances of finding a peaceful life.