Ruth, a woman of the desert people, knows about survival in the extreme conditions of the future, having learned from her Goshute, Mexican, and Mormon ancestors. Then a stranger comes to the Family cave, and she has the strong premonition that his knowledge and experience might be more valuable to the Family's survival than the water in his blood. After saving his life, she sets off with him into the desert, hoping to keep him alive long enough to discover what he knows. What begins as Ruth's impulse to save herself and those who live with her ends in a journey to the walled city of Salt Lake and to the western ocean, where she faces a harrowing choice.,Adapted from a summary by the author.