When Briony first meets Ren, he is standing in the freezing sea at the edge of their tiny town. Ren hasn’ t been home for a decade but has returned to be with his dying father. Briony won’ t leave, hoping that Sarah, her missing sister, will one day reappear. But Sarah and her friend Aria have been stranded on a desolate island far off the coast. The longer they’ re trapped there, the less alone they seem. How many secrets in this town have been swallowed by the brooding sea?