ET recently caught up with Appleby, who opened up about how she managed to leave her own mark on the series amid its many narrative twists and turns.
Wednesday night's episode -- spoiler alert! -- was drama-filled, with a hospital-bound Caitlin (Sydney Park) confronting her politician mom over cheating on her other mom with a man. Mason (Noah Gray-Cabey) also stops by to visit Caitlin in the hospital, forgiving her for hitting him and apologizing for blackmailing her and her friends.
Meanwhile, Ava (Sofia Carson) and Dylan (Eli Brown) team up to get Mason's phone back from the sewer. After they're chased underground -- by someone wearing a pig mask! -- they find out that Dana Booker (Klea Scott) has beaten them to the phone. She claims that its contents give Mason an alibi during Nolan's death, and that, coupled with all the other events of the episode, lead the trio of pals to guess that Dana herself is the one harassing them.
In between all of this, Taylor (Hayley Erin) is found safe and sound. Alison (Sasha Pieterse) even convinces Taylor to reveal her very-much-alive status to her mom.
The biggest reveal of all, though, happens when Mona (Janel Parish) finds a Beacon Guard unit at Taylor's trailer. The last frame of the episode shows Mona's shocked expression as the security system gets a notification that Nolan -- who the audience saw impaled by a spiked fence at the end of the pilot episode! -- is in motion and at Mona's apartment.
Despite that shocking reveal and the show's intense, winding plot, Appleby actually saw the episode as "a big thematic episode of people being alone and feeling lonely."
"We have Mona who goes out to the trailer... and she’s out there, by herself, looking for Nolan. And by the end of the episode she finds that he’s, like, out roaming around campus," Appleby explained. "Caitlin’s by herself in the hospital and her mom comes to see her. She has all of the visitors, but she’s always alone... Ava and Dylan are, like, chased through the sewers, but still, they’re on their own."
"It’s a lot of characters that are searching for connection," she added.
Appleby, who worked to include "as many Hitchcock references into the language as possible," tried to figure how to make the episode "visually stimulating and keep the characters moving," something she accomplished in the opening, seven-page-long hospital scene through 360-degree shots of Mona, Alison, Ava and Dylan discussing the situation.
Additionally, the 40-year-old director was able to use her time on UnREAL to inform Ava's dirt-and-glamour filledfashion show. "I got lucky that I was shooting the fashion show and I could sort of invoke that UnREAL behind-the-scenes chaos," she said of the Lifetime series where she played a producer on a Bachelor-esque show.
"I think directing always comes from grounding things and telling really truthful, emotional stories," she added of the episode generally. "... I feel like we just really nailed those stories and showed different sides of these characters that we haven’t seen before."
Despite the significantly heavy nature of the show, Appleby made it a point to maintain some sense of levity throughout her time on set.
"At the end of the day, the kids want to have fun. So it’s like, how do we show as much of their personalities even though they’re dealing with heavier topics? Because it still has to be fun and entertaining," she said. "... I had the best time working on the show. The girls were so wonderful. All the actors were. The show and the world is so much fun."
Aside from directing Perfectionists, Appleby has also helmed an episode of Roswell, New Mexico, and is gearing up to direct episodes of both Dynasty and Light as a Feather. For Appleby, directing YA shows with young stars gives her a chance to pass on all the knowledge she's learned throughout her career, which really took off when she starred on the original Roswell from 1999 to 2002.
"It's like teaching somebody something about the camera or lighting… teaching them how to maneuver that and manipulate that so that they always hit their marks and find the lens and look their best," she explained. "Or it’s about, 'Hey, maybe you’re nervous and you don’t realize when you're nervous, you're blinking a lot or you're taking a lot of breaths. I know you’re trying to convey this, but it’s really saying this to the camera.' And, like, pushing that information forward."
In addition to her on-set advice, Appleby makes sure to include some practical words of wisdom for the young actors she works with.
"I'm like, 'Are you saving your money? Are you saving your money? Are you saving your money? Let’s buy a house. Let’s save your money,'" she said. "A lot of kids get off these shows and they have no money left. I just feel like a voice of reason."
Along with her star-making stint on Roswell, Appleby has made waves on series including UnREAL and Life Unexpected, two shows that she'd "love" to see get the reboot treatment.
"I would love to reboot it if they wanted to," she said of UnREAL. "Rachel Goldberg was, like, the hardest thing I've ever done in my life," she said of her producer character on the series, which wrapped its final season last year. "Just an intense character and I feel so grateful to have played her. If they could figure out a way to have her do it again I’d be happy to."
As for Life Unexpected, she said that she wants to do a reboot of it "so bad" and revealed there have been discussions about a possible revival.
"We would love it," she said of bringing back the family drama, which ran for two seasons from 2010 to 2011. "We’re all really close. We just all took a camping trip together... all the writers, all the actors, all their husbands and wives and kids. I feel like there's a show there. It'd be really cool. [Creator] Liz Tigelaar and I have talked about it a lot."
Pretty Little Liars: The Perfectionists airs Wednesdays on Freeform.