Since the age of twelve, McKenzie Arnold has spent every summer at Albany Beach, Delaware, with her best friends Aurora, Janine, and Lilly. The seaside house teems with thirty years of memories - some wonderful, others painful - and secrets never divulged beyond its walls. This summer may be the last they spend together, as Janine contemplates selling her family cottage. For now, all four enjoy morning beach walks and lazy evenings on the porch, celebrating Lilly's longed-for pregnancy and offering support during McKenzie's greatest crisis. It's a time for laughter and recriminations, a time to forge a new understanding of a long-ago night when Aurora sealed their bond with one devastating act. And as the days gradually shorten, events will unfold in ways that none of them could have predicted, to make this the most momentous summer of all.