In a converted Georgian townhouse in south west London, three families live under one roof. The large flat that takes up the top two floors is home to the Harlow family: happily married Paul and Steph, and their bubbly teenage daughter Freya. The smaller first floor flat is rented by Emma, who spends most of her time alone, listening to people coming in and out of the building. And the basement flat belongs to Chris, a local driving instructor, who prefers to keep his personal life private from the neighbours. But their lives are all upended when Freya vanishes. As the police become involved and a frantic Paul and Steph desperately search for answers, they begin to realise that the truth behind their daughter's disappearance may lie closer to home than they were expecting.