Today is the day Ivy Moxam escapes from the cellar, her prison for the last 13 years. After she makes a desperate 999 call from a phone box, Ivy is picked up by the police and taken to be interviewed. With no precedent to follow, DI Elliott Carne and DS Lisa Merchant question Ivy to see if she is who she claims to be while they wait for official DNA confirmation. But before they can confirm her identity, news of her escape is leaked and the police rush to contact the Moxam family before they hear it from the press. When the family is reunited, younger sister Emma is the only person with doubts; mother Christina and estranged father Angus need no proof that Ivy is their daughter. The police finally locate the house in which Ivy was held captive, but find her kidnapper long gone. Combing the house for clues, Merchant and Carne discover evidence that contradicts Ivy's story - and Merchant starts to question whether or not she's telling the truth.