The Kingsway detectives are called in when the body of a young woman is found caught in a weir in a national park. It is learned the woman, a primary school teacher, was involved with a group of swingers, leading detectives to suspect the involvement of someone from within the group. The reported disappearance of another woman becomes a key element in allowing Joe and Harriet to solve the case. Despite his persistence, Sophie avoids Theo's overtures as she continues to keep details of her private life just that.
