Littleport, Maine, has always felt like two separate towns: an ideal vacation enclave for the wealthy, whose summer homes line the coast, and a simple harbor community for the year-round residents, whose livelihoods rely on service to the visitors. Typically, fierce friendships never develop between a local and a summer girl, but that's just what happens with visitor Sadie Loman and Littleport resident Avery Greer. Each summer for almost a decade, the girls are inseparable-until Sadie is found dead. While the police rule the death a suicide, Avery can't help but feel there are those in the community, including members of Sadie's family, who blame her. Someone knows more than they're saying, and Avery is intent on clearing her name before the facts get twisted against her.