Each summer the wealthy, seemingly perfect Sinclair family meets on their private island. Cadence, Johnny, Mirren, and Gat are a unit, especially during "summer 15," marking their fifteenth year on Beechwood-- the summer that Cady and Gat fall in love. Cady became involved in a mysterious accident, in which she sustained a blow to the head, and now suffers from debilitating migraines and memory loss. When she returns to Beechwood during summer 17,...