The body of missing schoolgirl Chloe Parks is found in a derelict hospital building, but Crime Scene Examiner Lorna Hart cannot confirm the cause of death. Stone is called to identify the girl's body. Suspicion immediately falls on the victim's boyfriend, who seems to be responsible for recent changes in her behaviour, but a chilling home video given to the police by a classmate changes the direction of the investigation. While Sam and Smithy investigate the circumstances leading to her death, Will acts as family liason officer.