In the GCPD, Commissioner Essen (Zabryna Guevara) gives orders to arrest the Maniax with Gordon (Ben McKenzie) leading the investigation.
Gordon tries to get Bullock (Donal Logue) back into the GCPD but his fiancée Scottie (Maria Thayer) is against his wishes as she fears for his life.
Bruce finds Alfred in a station, telling him he regrets what happened and re-hires him when he intends on training him, but making him fix the computer.
Lee (Morena Baccarin) survives by hiding in her lab while Nygma (Cory Michael Smith) saves Kringle (Chelsea Spack) from a gunshot.
The episode received a rating of 100% with an average score of 7.9 out of 10 on the review aggregator Rotten Tomatoes, with the site's consensus stating: "'Knock, Knock' combines over-the-top villainy and thrilling action to make for lurid spectacle.
""[3] Matt Fowler of IGN gave the episode a "great" 8.0 out of 10 and wrote in his verdict, "'Knock, Knock' wasn't a smooth ride, but parts of it did feel like the series was newly reinvigorated with focus and confidence, fully embracing madcap violence.
Club's Kyle Fowle gave the episode a "B" grade and wrote, "'Knock, Knock' sees this season's ominous villain and all around rich dude Theo Galavan begin to put his plan in to place.
For the second straight week Gotham shows signs of shedding many of the issues that bogged down its first season, from tone-deaf comedic beats to paper-thin characters, and moving towards something more focused.