While Bruce Wayne is starting on his path to become the Dark Knight, a dark secret of Gordon is threatening to bubble up in the surface, new spoilers for the "Gotham" season 2, episode 15 revealed.

Penguin found himself being an outcast, and must figure out a way to get back on top. It's one of the challenges for the writers and producers of the cast to make it seem like new information when everybody knows that all the villains in the show will end up threatening Gotham.

Previous spoilers for "Gotham" season 2, episode 15 revealed that Paul Reubens will join the cast as Elijah Van Dahl, Penguin's estranged dad.

Paul Reubens ("Pee Wee Herman") has shown before that he can play a delicious villain when he also played Mr. Vargas on "The Blacklist" so it would be interesting to see any hint of quirkiness and quiet menace that the Penguin possesses.

The synopsis for "Gotham" season 2, episode 15 teases plenty of spoilers as it reads:

"Gordon and Bullock investigate a trail of clues left in a museum robbery, which, unbeknownst to them, were left by Nygma in a dangerous game of cat-and-mouse. Meanwhile, Gordon's past comes back to haunt him when an anonymous person threatens to expose his hand in Galavan's murder. Also, Penguin's visit to some old friends leads him to meet his father, Elijah Van Dalh (guest star Paul Reubens), and Bruce practices his street smarts."

"Gotham" season 2, episode 15 airs on Monday, Mar. 21 at 8 p.m. on Fox. Watch out for more spoilers for the hit TV series.

Watch the "Gotham" season 2 episode 15 promo below.