According to Peter Hastings (Nolan North), Jessica's twin sister Mary (also Andrea Parker) is the one who killed Alison's mother and buried her in the Hastings' backyard. In his version of events, the murder was a malicious attempt for Mary to get back at Jessica and Peter for lying to her about her eldest child Charles dying. Charles, of course, never died. He transitioned into Charlotte (Vanessa Ray) and began a life of playing cyber bully with the Liars.
Of course, Peter Hastings has never been one to tell a straightforward story, so we can't be entirely sure that his version of events is actually what happened the night that Jessica died. TVGuide.com talked to Andrea Parker about the reveal and what Mary's next move is now that her biological daughter Spencer (Troian Bellisario) thinks she's a stone cold killer.
We got the reveal of the killer from Peter Hastings, who is not the most reliable source. How much of Mary's version going to match up with what Peter told us?
Andrea Parker: Since I'm loyal to Mary, let me give you her perspective. I think Peter lies like a rug. That's what I tweeted last night. The two of them really get around... Quite frankly, I think that Mary tricked Peter into thinking he was with Jessica. As we saw in the episode last night, that's not the first time she's done that, pretended to be her sister. Who knows what really happened? Last night's episode was so intense. Let me tell you, it doesn't let up. It increases from here. I don't know if that's good news or bad news for you. There will be more revealed about what happened the night that Jessica was murdered, how that went down and how Peter is related.
Did you get to film a flashback where you kill yourself?
Parker: We are not going to see the actual murder, but we are going to understand what and why and how it happened.
Spencer has already been trying to deal with some very complicated feelings about whether she wants to know Mary Drake or not. How does this further complicate their ability to have a relationship?
Parker: Immensely. That's pretty much the crux of what the two of them will be dealing with for the rest of the series, is how to navigate their relationship.
Mary has been hiding out since Spencer got shot. Are we going to see her start to reach out or is Spencer going to have to actively go after her even more?
How does that work?
Parker: You will see more and more of Mary as the series closes. All will be revealed! The last few episodes are beyond.
The case for trusting Mary or giving Mary the benefit of the doubt is looking really bad right now. Why should we be on Mary's side at this point in time?
Parker: In the world of [Pretty Little Liars] people act on instinct and they have very few filters. You have to watch your back in Rosewood. From Mary's perspective, she was acting out of self-defense.
What is Mary's goal by the end of the season? What does she want to accomplish?
Parker: I'm just going to give you one word: family. She has always wanted a family. Mary was ostracized and I think that Mary thinks that a lot of her childhood pain comes directly from Jessica. These two sisters have been going at it their entire lives. They have never been close. They have always had a volatile relationship.
How does Mary feel about Alison and how would her niece fit into that family she wants?
Parker: There's genuine love...I'm personally completely freaked out for my girls, for Emily and Ali, who are traumatized at the moment. A.D. is a savage.
How will Mary feel when she finds out that Alison is pregnant and if Mary will play a role in that?
Parker: It's her family. She's going to have to deal with it. I think that Mary is still misunderstood. There's still a lot more to be revealed about why Mary behaves the way that she does. I think that her love for Spencer and Alison is deep and genuine.
Is there a favorite Mary moment coming up that you can tease?
Parker: Oh my God, you're torturing me!...There are stunts involved.
Pretty Little Liars will return Tuesday, May 23 at 8/7c on Freeform.