In the season finale of Gotham's season one, Bruce Wayne (David Mazouz) and Alfred Pennyworth (Sean Pertwee) discovered a hidden compartment below the Waynbe Manor but Mazouz warned not to call it the Batcave just yet.

"It's definitely not the Batcave," Mazouz, told TV Insider. "It changes everything in Bruce's life. It changes how he sees Alfred, the criminal side of Gotham, even how he sees his parents...What is down there are clues to Thomas Wayne's secret life and what he was trying to do before being killed."

In the season-ender, it was teased that Bruce and Alfred descending into the mysterious cavern underneath the Wayne Manor that Bruce's father Thomas, had used for some secret purposes.

The discovery of the mysterious cavern could signal the beginning of Bruce's transformation as the Batman. However, Ben McKenzie, who portrays the character as Commissioner James Gordon, said that the writers and producers of the series plan on revealing Batman until the last possible moment of the series.

Gotham Season 2 will have regular bad guys, including Drew Powell's Butch Gilzean, Chris Chalk's Lucius Fox, Nicholas D'Agosto's Harvey Dent, and Morena Baccarin's Dr. Leslie Thompkins.

But fans of the series should also expect more bad guys as more of them are set to be introduced. The next season will see the appearance of Clayface, the Mad Hatter, Mr. Freeze, Hugo Strange, Tommy Elliot, and potentially even the Court of Owls. The early episodes will provide hints on the "pre-embryonic" origin story for the Joker.

Gotham Season 2 will also feature Michael Chiklis as Captain Nathaniel Barnes, Jessica Lucas as Galavan's sister (and future Tigress) Tabitha, along with Dustin Ybarra as a homicidal cannibal and James Frain as sinister philanthropist Theo Galavan. Victoria Cartagena and Andrew Stewart-Jones have also been downgraded from their series regular roles of Renee Montoya and Crispus Allen.

Fox also released the official trailer for Gotham showing the Joker will have the biggest impression in the next season. If anything, Joker will have a central role in the next season and because actor Cameron Monaghan, who plays the most hated Batman villain, has a laugh that is very classic Joker. Check out the new Gotham S2 trailer, complete with looks at the current state for a bunch of the show's villains.

Gotham will return to FOX on Monday, September 21.