She arrived into Heathrow after a difficult week at work. Her bag had been stolen. Her whole life was in there – passport, wallet, house key. When she tried to report the theft, she couldn't remember her own name. All she knew was her own address. Now she is at the door of Tony and Laura, a young couple living in Wiltshire. She says she lives in their home. They say they have never met her before. One of them is lying. But which one?