There's One 'Pretty Little Liars' Mystery That Will Never Be Solved & It's A Major One

After seven seasons, we're in the home stretch as we prepare for "Pretty Little Liars" to conclude this summer. Needless to say, there are a lot of unanswered questions and mysteries to be solved.

Everyone is theorizing about Uber A's identity, but that's not all. Who killed Jessica DiLaurentis — or is she alive and masquerading as Mary Drake? Does Spencer have a twin out there? What's the deal with the creepiest board game since Jumanji?

Although viewers have been promised that all those loose ends will be tied up, Shay Mitchell has revealed that one "Pretty Little Liars" mystery will never be solved — and it's a major one.

Remember that time the Liars' moms had one job, and it was to look out for their daughters on prom night? Instead, they had a little too much to drink and got locked in the DiLaurentis' basement.

Meanwhile, Ali, Aria, Emily, Hanna, and Spencer snuck off to prom in search of A (who turned out to be Charlotte). One mystery was solved, the girls went off to college, and the show returned after a five year time jump.

The moms are alive and well (phew!), but fans have been clamoring to learn how they got out of the basement. And, I mean, how long were they stuck down there? We have so many questions.

During an interview with Entertainment Tonight, Mitchell said this mystery will be one for the ages:

"I honestly think that this season, everybody's questions, no matter what they were – except for the moms and how they got out of the basement – that will never be answered, but everything else we will find out in this last eight episodes."

Wow. It's going to take a few minutes to process this. If it's any consolation, Mitchell promised that the other reveals will be jaw-dropping. "Our writers are complete geniuses and I would expect nothing less. I mean, they completely blew it away," she said.

We're going to hold her to that. If we never get to learn how the moms escaped, the Uber A reveal better be a doozy.

Citations: Shay Mitchell Reveals the One Question Pretty Little Liars Will Never Answer (Teen Vogue), EXCLUSIVE: Shay Mitchell on the Father of Ali's Baby & the One 'PLL' Question That Won't Be Answered (Entertainment Tonight)