Livia Denby is on trial for attempted murder. The jury have reached a verdict. Two years earlier, Livia was a probation officer in Yorkshire, her husband Scott a teacher. Their children, Heidi and Noah, round out a happy family - until the day Scott's brother dies. Grief and guilt leave Scott searching for answers, which take him into the world of conspiracy theories, his grip on reality weakening until he disappears with the children. As the authorities launch a search, Livia begins her own and discovers that Noah's life is in appalling danger. Livia's family has been torn apart, and now her son's life is hanging in the balance. Just how far will she go to save the ones she loves?