Francisco Cantú was raised by his mother, a park ranger and daughter of a Mexican immigrant, in the scrublands of the Southwest. After college, Cantú joins the Border Patrol. He and his partners are posted to remote regions of Arizona, New Mexico and Texas, where they learn to track other humans down drug routes and smuggling corridors under blistering sun and through frigid nights. They haul in the dead and deliver to detention those they find alive. Cantú tries not to think where the stories go from there. Plagued by nightmares, he abandons the Patrol after 4 years for civilian life. But when an immigrant friend travels to Mexico to visit his dying mother and gets arrested upon his return, Cantú must know the whole story.