A warm June evening, a local tradition: the students of Nantucket High have gathered for a bonfire on the beach. But what begins as a graduation night celebration ends in tragedy when Penny Alistair's car crashes, leaving her dead and her twin brother in a coma. The other passengers, Penny's boyfriend Jake and her friend Demeter, are physically unhurt - but the emotional damage is overwhelming.

As summer unfolds, details of that devastating night continue to surface. Questions linger about what happened before Penny took the wheel, and startling truths emerge about the survivors and their parents: revelations of secrets kept, promises broken . . . and hearts betrayed.