Rose lives a small-town life with her single mother Alma. Their luck takes a turn when Alma's new boyfriend, Derek, whisks them away on a sailing adventure. While at sea, Derek's shady past is revealed when their boat is attacked by savage villains, and Alma is viciously killed. Distraught and persecuted, Rose unearths a primal instinct of survival and a terrifying need to avenge her mother's death.