Fourteen-year-old Luce reaches the depths of despair when she is assaulted and left on the cliffs outside of her grim, gray Alaskan fishing village. She expects to die when she tumbles into the icy waves below, but instead undergoes an astonishing transformation and becomes a mermaid. A tribe of mermaids finds Luce and welcomes her in—all of them, like her, lost girls who surrendered their humanity in the darkest moments of their lives. Luce is thrilled with her new life until she discovers the catch: the mermaids feel an uncontrollable desire to drown seafarers, using their enchanted voices to lure ships into the rocks. Will Luce be pressured into committing mass murder?