Detective Cassie Maddox is still trying to deal with the events of 'In the Woods'. She is out of the Murder Squad and has started a relationship with fellow detective Sam O'Neill but is too badly shaken to commit to Sam or to her career. Then Sam is allocated a new case, that of a young woman stabbed to death just outside Dublin. He calls Cassie to the murder scene and she finds the victim is strangely familiar. In fact, she is Cassie's double. Not only that, but her ID says she is Lexie Madison, the identity Cassie used years ago, as an undercover detective...