I. Marlene King brought the dark, devious world of Pretty Little Liars to television in 2010 and has been freaking viewers out ever since. Here, she chooses her 10 scariest scenes from the series so far, giving insight into how her show became "Hitchcock for Teens."

1. The opening scene of the pilot, when Ali scares the Pretty Little Liars in the barn. (Episode 101)

I think we did a good job showing where we were going, in terms of how we were going to scare people on Pretty Little Liars. It's not just like, "Boo!" It's scares that come through tension and character and suspense. One of the reasons this scene still resonates for me is that whenever I see it, I always have to watch the whole scene — you want to see Ali pop in there, and then get that sigh of relief.

2. When Ian fights Spencer in the Bell Tower, and A shows up. (Episode 122)

Lesli Glatter, who directed our pilot, came back to direct this [episode] for us, which was really special and felt like a great bookend to the [season]. This was our first real reference to a Hitchcock film; we talked about Vertigo a lot, and we sort of visually recreated that, which helped build the tension. That's when critics started calling us "Hitchcock for Teens," and we realized that was our sweet spot. We realized our fans loved to be scared, and we fully embraced that. We call it the Ho-Ro [horror/romance]: Our fans want romance and they want to be scared, and we have so much fun giving that to them.

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3. Spencer is ready to defend herself against an intruder but it turns out to be Toby. (Episode 201)

I think this is what great suspense is all about: the lights are off, you're cowering behind a counter, there's a sigh of relief, and then we scare you after you have that sigh of relief.

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We were just starting to talk about the fact that Toby would eventually join the A team, so there was a little foreshadowing there, and I think that's why it's one of my favorite scares. I also really love Toby, so any scene where he ends up being embraced is going to be a favorite of mine. We've asked Keegan [Allen] to do so much; in the beginning, he was shy, and then he became the Jesus Christ of Rosewood. He was the only person in the cast who had never told a lie, and even when he joined the A team he was still making the ultimate sacrifice for Spencer.

4. A gives the Pretty Little Liars their dolls. (Episode 212)

In the book, Sara Shepard thematically introduced this idea — that Alison treated the Pretty Little Liars as if they were her dolls — and now A plays with them as if they're A's dolls. It felt like the perfect opportunity to introduce real dolls into the show. These dolls are creepy! And talking dolls are even creepier.

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We took the doll idea and ran with it; any chance we get to put a creepy doll in the show, we will … Emily's driving in her car and she looks in her rearview mirror and there's a little Chucky doll staring at her from the back.

5. Emily passes out in the barn and Alison saves her. (Episode 212)

This is one of my favorite scary scenes, because I knew when I was writing it that that Alison really was alive. This was Alison really saving Emily and really speaking her truth to her — she was the hardest to leave — and that's what I love about it. Alison is saying, "You can come with me if you want." She was willing to take Emily. And I think Emily was on the verge of that, and A was so close to winning.

Going back to the theme of the show, Ali isn't always the good guy and Ali isn't always the bad guy. She's a very complex character, which you see here. [She and Emily] have such an interesting relationship. What I love is letting these two characters figure out what their relationship is as the show progresses. It is complex, and it's not black or white, and there are a lot of layers to that relationship that we're going to continue to uncover as the show unfolds.

6. Emily faces off against A in the greenhouse. (Episode 214)

This was Emily's first action scene. Shay Mitchell [who plays Emily] likes to do her own stunts. I think what was so scary was seeing A finally facing off against one of the Pretty Little Liars. At this point, this was as close as any of them had ever been to A. We came up with the special balaclava, which everyone called the baklava on the show, and we had to put mesh in the eyes because we didn't want to see A's eyes. It just makes A so scary.

7. The shower scene at Lost Woods resort, when Hanna takes a shower and A comes into the room. (Episode 225)

This was our big season-two finale, and we're getting our Hitchcock on. Lesli Glatter directed, and we embraced the idea of the Lost Woods resort as our Psycho motel. I knew from the beginning that I wanted a shower scene — we couldn't do Psycho without a shower scene. Lesli recreated, almost shot for shot, some of the shower scenes from that movie.

And Ashley [Benson, who plays Hanna] plays so much with those eyes — her eyes will tell you when she's scared and when she's not. I always say to directors, "We play the eyes on this show, so make sure you get lots of coverage of these girls and their eyes," because that's where we play the scares and the heartbreak and the love.

8. Spencer visits A's lair, and realizes Mona is A. (Episode 225)

This scene was so much fun to shoot, because that's the first time we get to see Mona owning the costume. We'd seen A in the show, but A was never played by Mona because we didn't want any of the actors to know who A was. That was the first time Mona put on the hoodie. Everybody came to the set for that moment — actors who weren't even working came to the set because we all wanted to see Mona as A. It was so magical and creepy ... It was A coming to life.

Janel Parrish [who plays Mona] became so badass when she put that hoodie and those gloves on. It was awesome. She kind of knew that she was A a few episodes before we shot this finale, and she really had to go to a different place. It's like, "I'm not Mona when I'm in this hoodie, I'm A, I'm a person who despises Hanna Marin." She almost became a character with two different personalities.

What I love about that scene is that we're close on Spencer's face as she puts it together — Mona didn't go back to the car for that gum, Mona was buying that cardigan several episodes before. I love that these are smart girls, and they're usually one step ahead of the audience, so the audience is constantly trying to keep up with them.

9. Emily realizes Nate isn't who he says he is. They fight at the lighthouse, Caleb shows up, Emily stabs Nate, Nate shoots Caleb. (Episode 312)

This was a natural, organic place to bring the show; it was a darker level and an extreme threat that wasn't A. I mean, Nate is psycho. The real scary part is the way things start to escalate within the scene and realizing that Paige is terrified when he drags her out of the closet. We added every scary element that we could — a lighthouse, fog, at night, scary guy who's not who he says he is, a gunshot — that was one of those really great sequences to pull off. It also escalated to the point where Emily kills someone. It was the ultimate Pretty Little Liar taking ownership of her destiny. Yes, it was in self-defense, but it ramped up the show to the next level. In that season, in season three, Emily was always the one that A identified as the weakest link because she was so loyal and sweet. From that point on she was no longer the weakest link — she became the strongest.

10. Ezra gets shot. (Episode 424)

We were playing with the theme of "what appears to be isn't real" again. That you thought they were in Philadelphia for the whole episode but they were really in New York was the cherry on top of the ice cream sundae. It was a lot of fun — the rooftop that we built on stage at Warner Bros. was there so the girls would have that beautiful windblown hair while we're having our action and our scares. How great was it to put a gun in their hands and hear them say, "Take off your mask"? It's one of my favorite scary moments because the girls are so empowered by the end of it. You know, Ezra comes to save the day but it's really the girls who end up with the gun in their hands, screaming at A.

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