Contains spoilers for this episode and earlier episodes.
Will and Julie Purcell ride away from their Arkansas home after telling their father they are going to meet a friend. When they fail to return, Tom searches the neighbourhood and calls the police. Detectives Wayne Hays and Roland West begin with the family's troubled home and the people who saw the children that afternoon. Their questions expose strained relationships without establishing who took the missing brother and sister.
Wayne and Roland speak with teacher Amelia Reardon, local teenagers and neighbours. Evidence in the bedrooms raises questions about Lucy's cousin Dan, who recently stayed with the family. Scrap collector Brett Woodard also attracts attention, and the detectives enter his house while he is absent. Wayne's military experience becomes useful during the wider search. Away from the main group, he follows traces through the woods, finds small dolls and discovers Will's body arranged inside a cave. Julie is still missing.
The case is also shown through two later moments in Wayne's life. In 1990, lawyers question the old investigation and tell him that Julie's fingerprints have appeared at an Oklahoma pharmacy, overturning what he thought was known about her fate. In 2015, Wayne records reminders for himself as his memory fails and a documentary crew asks him to revisit the case. Amelia is now dead, and his son Henry helps him manage a present increasingly interrupted by the past.