In Tumacacori, in the south of Arizona, far from home, Patrick Martin Ashbridge, known as "P. M.", lives a respectable and affluent life as a lawyer. He has long severed his roots and left behind his old life as "Pat," along with his family and first wife. Until one day, his brother Donald shows up—having escaped from prison, where he was serving time for attempted murder. P. M. has never mentioned Donald to anyone, and now he demands that P. M. help him flee to Mexico. As the border river swells during these days, the situation becomes increasingly tense...