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?