It’s hard to believe, but the 100th episode of Pretty Little Liars is right around the corner, and we’re to expect big things from the milestone installment. Check out what showrunner Marlene King had to tell Alloy Entertainment about the much-anticipated episode...

“I can tease that in our fifth episode, which is our 100th episode, a very big mystery will be solved,” Marlene revealed. “It will ask more questions, of course, but you will get closer to a mystery that PLLs have been talking about for one or two seasons.” PrettyLittleLiars.com added that, when they asked Marlene “Will we find out who ‘A’ is?”, Marlene shook her head. Well, we suppose that doesn’t surprise us. But what mystery might she be referring to?

Our biggest clue is that the mystery has been around for a season or two. This actually discounts a lot of the larger mysteries, such as the aforementioned “Who is ‘A’?” But what does it leave? Here are our top guesses:

  • Who killed Wilden?

  • What happened to Toby’s mom?

  • Who is Ali’s Beach Hottie?

  • Does Ali have a twin?!

  • What is Radley hiding?

We’ll have to wait until Season 5, Episode 5 until the big mystery is revealed, and we hope it’s worth the wait. Pretty Little Liars has teased answers in the past only to leave us feeling more confused than ever. Lately, the show has done a good job of delivering more tangible reveals, such as the fact that Ali is still alive and that someone did attack her the night of her “death.” Will this 100th episode fall into this category of “solved mystery” or the former, more nebulous and disappointed vein?

What mystery do you think will be “solved” in the 100th episode? Share your theories in the comments below!

Catch the next episode of Pretty Little Liars on June 10, 2014 at 8 p.m. ET on ABC.

Kayti Burt is a contributing writer for Wetpaint Entertainment with a penchant for all things pop culture. Follow her on Twitter and Google+!