Patrick Martin (Joseph Cotten), known as P.M., is a wealthy attorney and rancher in the border town of Nogales, Arizona. He returns home to find his brother Donald (Van Johnson) hiding in his garage. A former drunkard, Donald had been sent to the penitentiary five years previously for killing a man in a barroom brawl. It was in self-defense but P.M. hadn't defended his brother and he was convicted.