Set in the years just before and during the Second World War, the novel follows Billy Parham, a teenage boy living on a ranch in Hidalgo County, New Mexico. When a pregnant she-wolf begins killing cattle on the family land, Billy traps her, but instead of killing her, he makes an impulsive decision that shapes the rest of his life: he resolves to return her to the mountains of Mexico from which she came. This first crossing of the border ends in tragedy, with the wolf forced into a pit-fighting ring and Billy ultimately granting her the only mercy left available to him.
Billy returns home after months of wandering to discover his parents have been murdered by horse thieves and the family's horses stolen. He collects his younger brother Boyd, and the two ride into Mexico to recover what was taken from them, a quest that becomes increasingly dangerous and morally tangled. Boyd is gravely wounded, falls in love with a Mexican girl, and eventually vanishes into the country, choosing a life apart from his brother.
The third crossing sees Billy return alone, years later, searching for Boyd, only to learn his brother has died and passed into folk legend, remembered in corridos sung by people who never knew him. Billy exhumes his brother's bones to carry them home, an errand that strips him of nearly everything that remains.
Structured around these three journeys, the novel is punctuated by long encounters with hermits, priests, blind revolutionaries, and wandering gypsies, each offering Billy parable-like meditations on fate, God, storytelling, and the indifference of the world. It ends with Billy, now a young man emptied out by loss, weeping alone at the roadside in the false dawn of the Trinity atomic test, though he does not know what the light is.
The book stands apart from All the Pretty Horses in tone: darker, more philosophical, and more explicitly concerned with the impossibility of holding onto anything, whether a wolf, a brother, or a coherent story about one's own life.
