"Knock, Knock" is the second episode of the second season and 24th episode overall from the FOX series Gotham. The episode was written by Ken Woodruff and directed by Rob Bailey. It was first broadcast on September 28, 2015, in FOX. In this episode, Gordon is assigned in investigating the Arkham escapees, now calling themselves "the Maniax". Meanwhile, Bruce is getting closer to the truth about his father's office.