After fleeing London Justine Merrison plans to spend her days doing as little as possible. But soon after the move her daughter Ellen starts to seem strangely withdrawn. Checking Ellen's homework Justine finds herself reading a chilling story about a series of sinister murders committed at the family's new house. Why would she invent something so grotesque? Then the anonymous phone calls start: a stranger making accusations and threats that suggest she and Justine share a traumatic past - yet Justine doesn't recognise her voice. When the caller starts to talk about three graves Justine fears for her family's safety. If the police can't help she'll have to confront the danger herself but first she must work out who she's supposed to be…