Sixteen-year-old Billy and his brother Boyd are fascinated by an elusive wolf that has been marauding his family's ranch. Billy captures the animal – but rather than kill it, sets out impulsively for the mountains of Mexico to return it to where it came from. Billy returns, finding himself and his world have irrevocably changed. His loss of innocence has come at a price, and once again the border beckons with its desolate beauty and cruel promise.