Marcella investigates a serial killer of children, encountering a paedophile, an arrogant millionaire, a 1970s rock star, and strange symbols relating to witchcraft. Her estranged husband Jason has become engaged to his rehab nurse even though their divorce is not yet finalised, putting their children in the middle of a custody battle that quickly becomes ugly. Marcella's blackouts continue and she seeks counselling to help her remember what happened during them.