When Gina Vincent receives a letter of condolence from a stranger following her mother's death, a photograph slipped inside reveals a disturbing truth - everything she's ever known is based on a lie. Shocked and disorientated, she engages genealogy detective Esme Quentin to help search for answers. The trail leads to an isolated and abandoned property on the edge of Exmoor, once the home of a strict Victorian institution called The House of Mercy and its enigmatic founder, whose influence seems to linger still in the fabric of the derelict building. As they dig deeper, Esme realises that the house itself hides a dark and chilling secret, one which must be exposed to unravel the mystery behind Gina's past. But someone is intent on keeping the secret hidden. Whatever it takes.