Pretty Little Liars will give fans a "twisted" ending to season 5.

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There's only one week left before the ABC Family drama unleashes a major 'A' reveal in "Welcome to the Dollhouse," and Sasha Pieterse (Alison) believes viewers will never see it coming.

"I do know who 'A' is, and it's very twisted, and I don't think anyone will see it coming. It's not something that you would expect or even that the viewers would be like, 'Oh, that makes sense.' It's actually very dark, especially for this kind of TV show," Pieterse explained to People. "I enjoy it, and I think it's got great places to go, and I know the writers are having a ball continuing writing for the sixth season and planning for the seventh season. We're very lucky, and I think the fans, it's literally going to blow their minds."

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Fans have been sifting through evidence for five seasons now, and the March 24 episode will see these hard-worn theories tested for the final time. Who do you think 'A' is? Sound off in the comments below!

Find out more when Pretty Little Liars airs Tuesdays at 8 p.m. ET on ABC Family. Click the video below to see a preview for the season 5 finale.