Fan favorite Janel Parrish makes an appearance as the Ghosts of Christmas Past, Present and Future

After August’s shocking Season 5 finale on which fan favorite Mona Vanderwaal (Janel Parrish) was brutally murdered, Pretty Little Liars viewers have been eagerly anticipating a return to Rosewood for some answers.

Now, the wait is almost over: The hit ABC Family drama, about an anonymous adversary who sends threatening messages to a group of girlfriends, returns Tuesday with its revered holiday episode – this time swapping the Halloween backdrop for Christmas.

For those concerned that Yuletide cheer might overshadow the usual mysterious and frightening aspects of the show, fear not. Showrunner Marlene King assures PEOPLE this episode will have the same level of scare and mystery as previous installments – just with a bit more mistletoe.

Christmas seems to offer fewer opportunities for scares than Halloween. What new plot opportunities does Christmas bring?
My children who have seen every episode of PLL watched the Christmas episode and said it was by far the most scary. Even though it’s not Halloween, the world we live in and the challenges the girls face and the life or death stakes “A” has presented them with give us a lot of opportunities for thrills and scares in this episode. I’m really happy about the balance that we struck. It’s very nostalgic and festive but at the same time really delivers on the scare.

Any hints you can give about Alison’s (Sasha Pieterse) four new friends seen in masks in the preview? Are they anyone we already know from Rosewood?
I will say that it is interesting to me that if you look at the masks, they look a lot like [the character] Spencer (Troian Bellisario). It’s interesting how they turned out. It is definitely Ali and a posse, and the reveal of those people is a really fun twist in the episode. You know all four of them.

Mona is playing the Ghosts of Christmas Past, Present and Future in this episode. Will the ghosts be a different character or have some of Mona’s signature personality?

A little of both. She is Mona embodying the ghosts. And Janel Parrish is so spectacular. She had so much fun with this episode, and it is really apparent on the screen.

What will be revealed in the future?
That’s one of the scariest scenes in the episode. She really shows Alison that if she doesn’t change her ways a very, very frightening fate will be coming her way.

What will we see in the past? Any familiar faces?
It’s a great scene. It’s one of my most favorite scenes in the episode. There’s a moment that Mona reveals to Alison that she had forgotten about. And it’s a moment in time where Alison is a little girl and there is an encounter she has with her mother that really is a big shift and a big part of why Alison becomes who she becomes.

Will there be a death in this episode?
I don’t want to say.

What is Spencer’s status? Has she been bailed out of jail?
She is out on bail and is still under arrest for Bethany’s murder. [The girls] are presented with an opportunity that should clear her name during the episode.

Will we have some answers in this episode or be left with even more questions?
There’s definitely some answers in this episode. The girls uncover some information that is key to our plot moving forward.

What is going on with all the couples in Rosewood? Are Hanna (Ashley Benson) and Caleb (Tyler Blackburn) together?

Part of the festive Christmasy fun of the episode is that all of our couples get a little Christmas romance.
When we finished last season, Emily (Shay Mitchell) and Alison were at odds. How are they now?
We left them very strained, so that’s where we start the episode as well.

What can you tease about the upcoming sixth season?
I love the upcoming season. It’s very different for us. We see some sides to the show we’ve never seen before. We are moving forward at a more rapid pace now. We just finished shooting the finale, and I’ll quote our director of photography when he said, “We can’t drop the ball on this one, it’s by far our most important episode to date.” That is a very big, special episode.

How much is Mona going to be in this upcoming season?
We see her in a flashback as well as the ghost of many Christmases in this upcoming episode. We all love getting to see her as much as we can. She is a very beloved character on this show. As I promised her when I made that phone call to her that she was going to meet her demise, we would continue to see her in flashbacks.

The Pretty Little Liars Christmas special airs Tuesday at 8 p.m. ET on ABC Family.