Part 2 of 3. Maggie re-interviews the Reids and their neighbors; and travels to Germany to talk with the au pair, whom she believes may be key to uncovering the truth. She also receives disturbing information about her son, which causes tension at home.
Part 1 of 3. The investigation into a little boy's disappearance is seen across two timelines: In 2008, when he vanished from a neighborhood barbecue; and five years later, after his body is found in a communal garden not far from his home. DCI Maggie Brand, who initially handled the case in 2008 before health reasons forced her to step down, takes control of the investigation.