The city of Gotham is in a state of uneasy transition. With Bruce Wayne incarcerated and The Joker gone, Harley Quinn now navigates a fractured life as a mother to her twins. This vacuum has been exploited by a figure known only as the Producer, who has recruited the cinematic serial killer the Starlet whose murders of old film stars have drawn the attention of the GTO and FBI Agent Hector Quimby, who see a disturbing link to the late Clown Prince of Crime. Forced to cooperate, Harley begins an investigation with Bruce’s remote guidance, a path that leads her back toward the very chaos she left behind.