'Pretty Little Liars' Boss Marlene King Talks 'A' Theories: 'Only One Fan Guessed the Truth!'

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Merry Christmas to all, and to all a good fright!

Merry Christmas to all, and to all a good fright!

Pretty Little Liars' first-ever Christmas special is almost here and even though we know it's going to be jam-packed with romantic moments, there are still going to plenty of the series' signature thrills and chills hiding under the tree.

To help get you prepared for all of 'A' holiday-themed antics, ETonline had an exclusive chat with PLL's executive producer Marlene King and we've got your inside scoop on an "explosive" reunion, the true identity of 'Big A' and more pretty little secrets.

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For those of you who are still crushed about the news of Rosewood's most recent jaw-dropping death, you can take comfort in the fact that Mona is coming back in Tuesday's special — and she's ready to torture her former tormentor.

Dressed as the ghost of Christmas past, present, and future, Mona will truly terrify Ali in a way that fans have never seen before. "You will definitely see [Ali] scared in this episode, and I love it." King confessed to ETonline.

"I think this is the most that we've ever seen Janel Parrish and Sasha [Pieterse] together on screen. They have such a great dynamic and they're really the two villains facing off," she continued. "It's explosive when we see them together, and Mona needs to scare Ali if she's ever going to make a difference in her life. She's got that goal when she starts out, and she succeeds."

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As for the questions surrounding Mona's death, King spilled that fans will get these answers "fairly soon." She explained, "There are some answers that start coming in the Christmas episode, and then right away when we launch in January, there are a lot of answers right at the top of 5B."

And speaking of answers, in PLL's Halloween special, viewers were shocked to learn that the identity of 'Big A' will actually be revealed before season seven starts. So of course, we had to ask King about the reason for this early unveiling.

"It just feels like the right time," she explained. "It felt like the right time at the end of season two to give up original 'A' and Mona through that reveal. And in terms of where we want to go with the show, as we move to the end of season five, this revelation needs to come sooner than later."

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There are plenty of theories and rumors swirling through the Internet about the identity of 'Big A,' but guess what? They're all probably wrong! King confessed that she has only seen the correct answer once.

"It's only been one time in the history of the show," she said. "Both my assistant and I saw it online — I won't even say where — but there was someone who had it completely right, and I think I saved it. If I have it, and once that revelation is revealed, I will call that person. It was shockingly correct."

So as of now only a handful of people truly know who has been hiding underneath that black hoodie for all these years. "Troian [Bellisario] and Keegan [Allen] know," King said. We were very late on set one night and I told them. And maybe Ashley [Benson] knows now too." (Umm, is anyone else insanely jealous right now?)

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So how can the fans figure it out? "There are going to be some clues given at the end of season 5B that I think really tell the story of where we're going," King answered. "I've seen so many fantastic theories that the fans have, but they will have a lot more information to base those theories on by the end of 5B."

Better start thinking harder little Liars because apparently only one of you has the correct answer…

Pretty Little Liars' Christmas special airs Tuesday, Dec. 9 at 8 p.m. on ABC Family.

Who do you think is hiding under those black hoodies? What are you most excited to see in the PLL Christmas episode? Sound off in the comments below or chat with our pretty little expert @LeanneAguilera on Twitter.