Teenagers Nell and Jude find the body of a young woman and when no one comes to claim her she becomes known as the Brighton Mermaid. Nell is still struggling to move on when three weeks later Jude disappears. Twenty-five years on Nell is forced to quit her job to find out who the Brighton Mermaid really was - and what happened to her best friend that summer. But as Nell edges closer to the truth dangerous things start to happen. Someone seems to be watching her every move and soon she starts to wonder who in her life she can actually trust…