After ten years away from London, 29-year-old Rona (Saoirse Ronan) returns home to the Orkney Islands. Reticent but lonely, she struggles to repress her memory of the events that set her on this journey of recovery. Slowly, the mystical land enters her inner world, and - one day - Rona finds hope and strength within herself amidst the violent storms and the bitterly cold sea.