When "Pretty Little Liars" returns tonight (June 2), Alison DiLaurentis will be on a mission to save her friends, who've spent the last month locked inside A's creepy dollhouse.

"She's scared, and she wants her friends back," Sasha Pieterse told MTV News ahead of the season six premiere. "She knows the situation is extremely dangerous, and A is capable of everything, which is even scarier. This is a really dark season, extremely dark -- darker than we've ever gone."

The darkness, it seems, will stem from A's origin story. In the season five finale, Spencer made a shocking revelation: Charles is A. But who is Charles? Pieterse did confirm to MTV News that Charles is a DiLaurentis, and as the Liars dig deeper into Charles' past, things will only get more twisted. And while the Liars know A's true identity, Ali has no idea... yet.

"Ali has no idea who Charles is, and that's what is kind of bizarre about it," she said. "This person comes out of the woodwork who is somehow related to her, and she had no idea."

"Charles is obsessed with these girls, and Alison, and what's you realize why, it's crazy dark," Pieterse added. "Charles is hyper-intelligent and his money is coming from somewhere. All the details that unfold are very unsettling."

Unsettling is one word for it. Of course, we'd prefer "totally f--ked up." Once the Liars begin to piece together the story of how Charles became A, they'll dig up plenty of DiLaurentis family secrets -- and Ali will ultimately come face to face with a haunting realization.

"There's a lot of crazy things that happen with her family, and this season, you'll realize why she's as messed up as she is," she said. "We've started to touch on that, but this brings it to a whole new level. There's a lot of stuff she was dealing with subconsciously that she didn't even know was."

Unlike last season, where the Liars' kept Ali at a distance, season six will them come together to take down A once and for all.

"It's not all Alison's fault anymore," Pieterse said. "To a certain degree it is -- certain things that she's done has lead them to this place -- but at the same time, this wasn't her doing. She's not A. So they really have to ban together. It's fight or die time."

But can the Liars really trust Ali? It's clear she's still hiding some secrets about her past ventures. However, it looks like former Queen Bee has finally turned over a new leaf in the wake of her friends' kidnapping.

"She is so genuine right now, especially," she said. "Prison really changed her. She's gone through a lot of different things, and her return home has been such a crazy reality check for her. She's had to grow up fast and realize what's important -- and right now, what's important is finding her best friends. She's going to work hard to earn their trust, and this isn't like last time, it's genuine. As much as she's scared for her life and for her friends, she's realized that she's got to let go of this fear she's been holding onto. It's not just about herself anymore; she's got to protect her friends."

Ali's newfound sincerity also puts her in a precarious position. The closer she gets to the Liars, the closer she gets to Charles -- and when it comes to his affinity for toys, Ali would be the ultimate prize.

"A wants to complete his dollhouse and that includes Alison," Pieterse warned. "Alison is the key -- the cherry on top of what he's been wanting, so she's definitely in danger. There are police cars outside her house, so they're protecting her as much as humanly possible. But we're dealing with A, and you're never safe when A is on the loose. So it's a scary time for Alison."