Bill Walker, a man still grieving for his late wife, is confronted with a problem: His small ranch on the Arizona-Mexico border is being used as a stopover by illegal immigrants who use the water from his stock tank to ease their thirst. One morning, while making his rounds, he encounters a Mexican woman near death from hunger, thirst, and exposure. For reasons not even clear to himself, he proceeds to hide the woman from his friends and the Border Patrol. The cops are the least of his worries, though, as intrigue and near-death danger reveal the woman to be much more than she initially appeared.