How Pretty Little Liars: Original Sin And Riverdale Are Connected

After six seasons (but, sadly, no movie yet) and two spin-off shows, "Riverdale" has gone from being the tale of an idyllic small town with a seedy underbelly to a saga about the cosmic battle between the forces of good and evil, pitting himbo-next-door Archie Andrews and his friends against serial killers, evil nuns, cult leaders, and, most recently, warlocks from other dimensions. In that sense, the series has lived up to its promise of being "Archie Comics meets 'Twin Peaks'" in ways that nobody could have predicted when its premiered on The CW in 2017.

As the show prepares to head into its seventh and final season, "Riverdale" creator Roberto Aguirre-Sacasa is already filling up his docket with future projects. In fact, he only just co-created HBO Max's "Pretty Little Liars: Original Sin," the latest addition to the "Pretty Little Liars" property — itself a shared universe almost as deliciously outlandish and murder-happy as the Archie-verse. Might one be so bold as to hope for a crossover between the two, given Aguirre-Sacasa's shared involvement? It's actually far more feasible than you might imagine.

Episode 6 of "Pretty Little Liars: Original Sin" season 1, "Scars," follows series leads Imogen (Bailee Madison) and Tabby (Chandler Kinney) on a journey from their homes in Millwood, Pennsylvania to Rosewood, Pennsylvania, the setting of the original "Pretty Little Liars" TV series. "We love the idea that Rosewood exists," Aguirre-Sacasa told Entertainment Weekly. "We reference it. There are Easter eggs throughout the season."

But the episode goes beyond connecting the different corners of the franchise, revealing that Riverdale itself (!) exists in the "Pretty Little Liars" universe.

Upon making their way to Rosewood as part of their investigation into the truth about Angela Waters (the teenager whose shocking death in 1999 serves as the catalyst for the show's events in 2022), Imogen and Tabby pay a visit to the Radley, a ritzy hotel that was once the Radley Sanitarium, another major "Pretty Little Liars" location. There, the duo learn Angela's mother was a patient at the sanitarium before it was closed down, with some of its patients being sent to stay with the Sisters of Quiet Mercy in Riverdale instead.

Who, you might ask, assuming you've never seen "Riverdale" (or even if you have; the series can burn through more plot in a single episode than some shows do in an entire season)? You see, back in "Riverdale" season 1, the Sisters of Quiet Mercy was thought to be a nunnery that doubled as a home for kids without parents or "troubled" youth, like Betty Cooper's then-pregnant sister Polly. But like so many things in The Town With Pep, the Sisters were not what they seemed on the surface.

The Sisters, to put it mildly, are bad news. They terrorized their "patients" with fantasy table-top role-playing games (would one call that inverse of Satanic Panic?), conspired with local mobsters, separated pregnant teen girls from their babies, and ran a conversion therapy program (among other things?!) prior to being arrested and seemingly dying by mass suicide to avoid paying for their crimes — although, in reality, one of their own killed the others. Suffice it to say, if you hear someone mention the Sisters, you should immediately sprint in the opposite direction.

If you're still trying to wrap head around the idea of "Pretty Little Liars: Original Sin" and "Riverdale" existing in the same universe, then buckle in: It gets even wilder.

Because all of the "Pretty Little Liars" TV series — at the very least, in theory — take place in the same reality, that means "Pretty Little Liars" lead Aria Montgomery (Lucy Hale) exists in the same universe as "Original Sin." However, Hale also played the titular role in The CW's short-lived "Riverdale" spin-off series, "Katy Keene," and even hung out with her old pal Veronica Lodge on an episode of "Riverdale" season 4. Does that mean Aria and Katy have doppelgängers of one another running around somewhere on "Original Sin?"

Before we go too far down this rabbit-down, it's worth recalling that "Riverdale" season 6 established the existence of a multiverse housing alternate versions of the Riverdale we already know (including one dubbed "Rivervale"). As such, it's possible the "Pretty Little Liars" reality is home to a different iteration of The Town With Pep, complete with a very different Katy Keene who lives in New York City. But what of Archie, Betty, Veronica, and Jughead Jones? Are they the same in this version of Riverdale? Is Sabrina Spellman even around? We need answers, dangit!

For now, viewers will merely have to satisfy themselves by imagining Jughead broodily narrating the plot of "Pretty Little Liars: Original Sin." The show is streaming on HBO Max, with "Riverdale" available to stream on The CW's app.