‘Pretty Little Liars: Original Sin’ boss: ‘It’s a slasher version’

“Pretty Little Liars: Original Sin” is billing itself as a “new chapter” of the original “Pretty Little Liars” story — and not a reboot. 

“Very early on, we decided we were going to invent new characters. We weren’t going to do a new version of [original series characters] Aria or Alison,” co-creator Roberto Aguirre-Sacasa, 48, told The Post. 

“We said, ‘That’s canon … but what’s going on in this town that’s a little bit removed from Rosewood [where the original show was set]? This town called Millwood, which is a less affluent town, is a rust belt town down on its luck. It’s a little grittier than Rosewood. It was like, ‘This will be part of the ‘Pretty Little Liars’ cinematic universe,’ as we jokingly call it. But there’s enough new stuff here.”

Premiering July 28 on HBO Max, “Pretty Little Liars: Original Sin” was co-created by Aguirre-Sacasa (“Riverdale,” “The Chilling Adventures of Sabrina,”) and Lindsay Calhoon Bring (another “Sabrina” alum). The series follows a group of girls whose mothers were all part of a tragedy 20 years earlier that ripped the town apart. Now, in the present, the girls are being tormented by an unknown assailant. The group includes horror movie buff Tabby Hawthorne (Chandler Kinney); quiet and quirky Minnie “Mouse” Honrada (Malia Pyles); ballerina Faran Bryant (Zaria); and pregnant teen Imogen Adams (Bailee Madison).

The original “Pretty Little Liars” aired on ABC Family/Freeform from 2010-2017 and turned Lucy Hale, Shay Mitchell and Ashley Benson into stars. Its plot followed a clique of teen girls that fell apart following the disappearance of their leader. 

“I was approached by my bosses at Warner Brothers, and they said, ‘What do you think about doing a new version of ‘Pretty Little Liars?’ Which is another way of saying, ‘We want you to do it,’: said Aguirre-Sacasa. “I had seen the pilot, because when I was developing ‘Riverdale,’ I watched every teen pilot that had ever been shot and made. I went back and watched a few more episodes, and it was compulsively watchable. Weirdly, I must have absorbed a lot from that pilot. Because I could see that ‘Riverdale’ probably wouldn’t have existed without ‘Pretty Little Liars.’ I understood why I had been asked to do it, because of the plotting of ‘Riverdale’ and the twists, and all that. 

“However, ‘PLL’ at its core is about teenage girls and their friendship and lives and dramas and loves. I quickly realized there’s a lot of things I can do, but I should probably partner with a writer [Bring] who can more authentically capture and speak to the journey of young women.”

”Pretty Little Liars: Original Sin” will lean more into the slasher genre, Aguirre-Sacasa said. 

“Lindsay and I, my co-creator, are huge horror fans. We were working on ‘Sabrina,’ a horror show. And ‘Riverdale’ certainly has horror elements in it. And the original ‘PLL’ flirted with horror. But none of these shows had a true strong horror slasher element.

“The idea of doing a horror/slasher version of ‘PLL’ where [the unknown assailant] ‘A’ was a villain like Jason from ‘Friday the 13th’ or Michael Myers from ‘Halloween’ or Freddy Krueger …feels like a way that we can honor the original show, and yet do something new and explore a new genre.”

But don’t expect to see Aria Montgomery (Hale) or the stars of the original show pop up. At least, not yet, Aguierre-Sacasa said. 

“Because the original is so iconic and we didn’t want this to feel like a spinoff, we gave ourselves the rule that for the first 4-5 episodes, we were really going to just be about introducing our world, our franchise, our characters, our villain,” he said. “From about Episode 6 and on, the easter eggs start coming fast and furious. There are characters from the original ‘PLL’ that are invoked pretty directly, and that’s all I can say. If you’re a fan of the original, I think it will be appreciated.”