Ruth and Simon Pierce's rare romantic break is shattered by devastating news: their daughter, Heather, on holiday in Cornwall with a friend's family, has disappeared. The loss is more than they - or their marriage - can bear. But time does heal, and slowly Ruth builds a new life for herself. A new husband, Andrew - even a second daughter, Beatrice. The chances that history could repeat itself are next-to-impossible - that is until, years later, a desperate phone call launches DI Will Grayson and his partner, DS Helen Walker, into an investigation which will test their professional and emotional resources to the very limit. Yet as Grayson becomes increasingly obsessed with a recently released child-abuser and Helen is drawn deeper into a destructive love affair with a married colleague, there is a real danger that their most demanding investigation yet will slip fatefully through their hands...