Jeffrey Pierce and Jonny Coyne, inset Matt Craven

Get ready to find out who is behind that mysterious door on Alcatraz!

The cast and creative minds behind the Fox series were on hand Sunday at WonderCon for a panel, moderated by this reporter, during which they teased the introduction of one of the powerful people pulling the strings. TVGuide.com has learned exclusively that the role will be played by Crimson Tide star Matt Craven, who has also recently recurred on NCIS and Justified. The character will be introduced in the season finale.

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"The new character is the guy behind the door," executive producer Daniel Pyne told TVGuide.com following the panel, recalling the "Cal Sweeney" episode when Warden James (Jonny Coyne) threatened a prisoner with meeting a "friend" downstairs. "Clearly, when you open that door in the past, there's a guy in there, and we had to know who that guy was. He turns out to be much stranger than you'd expect, and he's someone even the Warden is a little weary of. The new character is the perfect foil for the Warden."

Adds co-creator Steven Lilien: "He actually will provide us with some really big answers, which will launch us into Season 2." Those answers include who is actually helping the '63s assimilate and why some of them have come back with specific missions. "Some '63s are chosen very specifically, and we'll see that with Tommy Madsen (David Hoflin)."

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However, the Warden and the new character aren't the only ones behind this big mystery. In fact, we've already met someone else who is in on it. "There is another very important character, whom we've met, who will also be revealed to have his own agenda in present day," Pyne says.

But the show isn't saving all its shocks until the end. "The last five minutes of this Monday night's episode [9/8c, Fox] will change everything moving forward," co-creator Bryan Wynbrandt teases. In that episode, Rebecca (Sarah Jones) and Doc (Jorge Garcia) will finally be clued in on a huge piece of the puzzle. Plus: We'll get insight into Lucy (Parminder Nagra) and Hauser's (Sam Neill) relationship in the past, which will raise questions about how Hauser might feel about her in present-day.

Oh, and in case you're worried, Nagra says there's a "strong possibility" we will see Lucy out of her coma by the season finale.

Alcatraz airs Mondays at 9/8c on Fox.