The promo for the second season of "Gotham" has finally hit the web, and it teases the arrival, return and rise of several villains, including Jerome (Cameron Monaghan), who is expected to become the Joker.

The upcoming season "Gotham" will continue to explore the layers of corruption in Gotham and the development of iconic villains. The Riddler, Two-Face, Catwoman and The Joker will appear during the upcoming season, but "Gotham" star Ben McKenzie has also hinted at the appearance of other DC legends, like Superman. Then, according to ComicBook, McKenzie told a fan, "We're mainly focused on the world of Batman and Gotham. So we don't cross over into Superman. We do pull deeply from the canon. We have access to every single character in the world of Gotham."

Actor David Mazouz (Bruce Wayne) recently revealed the importance of the cave, stating that it changes everything in Bruce's life, including how he sees Alfred, his parents and the criminal side of Gotham. The cave will likely present some answers or clues, and it will shine a light on deaths to the Waynes. The entire first season led up to Bruce's discovery of the cave, and it will ease his transformation into Batman. The mysterious lair likely conceals many secrets.

"It's definitely not the Batcave," Mazouz cautioned. "What is down there are clues to Thomas Wayne's secret life and what he was trying to do before being killed."

The executive producer/writer of the series is Bruno Heller, and it stars Donal Logue, Sean Pertwee, Robin Lord Taylor, Erin Richards, Mazouz, Camren Bicondova, Zabryna Guevara, Cory Michael Smith, Ben McKenzie, Victoria Cartagena, Andrew Stewart Jones, John Doman, Natalie Alyn Lind, Jessica Lucas, James Frain, and Michael Chiklis.

"Gotham" Season 2 premieres Sept. 21 on FOX.

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