'Pretty Little Liars': Janel Parrish on Mona's 'Unlikely Alliance' and Season 4 (Video)

Is Mona conspiring against the girls?

It's one of many questions Pretty Little Liars will attempt to address in the fourth season, which bows Tuesday. For actress Janel Parrish, it's a fine line to walk, with Mona seemingly back in the Liars' good graces.

"She's become the fifth PLL, which is unexpected -- and a great new twist," Parrish said in a recent visit to The Hollywood Reporter Cover Lounge.

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As the actress tells it, season four introduces another side to Mona ("She's had like eight different personalities!" Parrish jokes). "It's an edgier but more humbled Mona. She's now 'A's' biggest target and she doesn't know why. She has to work with the girls to find out who the new 'A' is and who the new Red Coat is," Parrish says. "This is the most real Mona has been since I've been playing her. She's no longer putting on any pretenses, she's just Mona. She's manipulative, very smart, tough, edgy and not someone to be trifled with."

But with "A" breathing down her neck, Mona is in even more danger than ever before -- thanks to his or her willingness to be aggressive in his or her attacks. "This new 'A' is worse than anything Mona's ever done," she adds. "There's nothing they wouldn't do, so this is the most dangerous 'A' we've ever faced."

With Mona joining the ranks of Aria (Lucy Hale), Hanna (Ashley Benson), Emily (Shay Mitchell) and Spencer (Troian Bellisario), the very same girls she tormented over the past few seasons, Parrish describes the "team-up" -- if you can call it that -- as "an unlikely alliance, and a reluctant one at that." Executive producer Marlene King had her own take on the Liars' newest addition when she spoke to THR: "In some ways, it's still a mystery. In some ways, it's comical. In some ways, it's so heartfelt.

"[Mona] doesn't like the girls, they don't like her. Ultimately they know they have to learn to trust each other, because they're now in this together," King said of the girls' fight against "A." "It's definitely a different dynamic than we've ever seen." 

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As expected, not everyone welcomes Mona with open arms. The Liar that may have the most difficult time is Emily. "Emily's the tough mother of the group, and she takes it upon herself to protect them," Parrish says. Naturally, that leads to confrontation: "Mona and Emily have a bit of a rough tension going on for the first few episodes," she hints.

Bellisario likens Mona latching on to the girls to "being cast away on a desert island with your friends and then your worst enemy. It's like, 'Well, we have to trust you.' It's like Lord of the Flies land, but we don't want to. It's definitely a push and pull."

And because Mona is closer to the group than ever before, the first thing on her to-do list is to mend her currently nonexistent friendship with former bestie Hanna.

"Her first aim is to make Hanna trust her again. She really did love Hanna, and if there's ever been a soft spot for Mona, it's been her," Parrish says. "Mona will definitely reach out to Hanna, and they might form a friendship again."

But there will certainly be obstacles (see: Mona running Hanna off the road with her car). "Yes, Mona's done a lot of terrible things to the girls. Hanna will definitely have a hard time trusting her, but if they can find an in-between, they will," she promises.

Pretty Little Liars premieres season four at 8 p.m. Tuesday on ABC Family.

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