For Polly, the small town of Livingston, Montana, is a land charmed by raw, natural beauty and a close network of family that extends back generations. But the summer of 2002 finds Polly at a crossroads: a recent head injury has scattered her perception of the present, bringing to the surface long-forgotten events. As Polly's many relatives arrive for a family reunion during the Fourth of July holiday, a beloved friend goes missing on the Yellowstone River. Search parties comb the river as carefully as Polly combs her mind, and over the course of one fateful week, Polly arrives at a deeper understanding of herself and her larger-than-life relatives.