According to this synopsis, the Liars have learned something new about their dead frenemy — we're guessing it's something revealed at the end of Episode 20 — and whatever it is, it's enough to make them change their minds about Alison (Sasha Pieterse). After spending most of the season thinking she's "A", the Liars now want to get Ali out of jail! It sounds like they've realized that Ali is not, in fact, the killer... or that Mona has secretly been alive this whole time. (Hey, we're not going to give up hope yet.)
Whatever this secret it, apparently Mike knew something about it, and Aria realizes that his involvement "could have serious repercussions for her family." Was he hiding evidence? Or are the repercussions be "A" related in nature?
Meanwhile, "Spencer heads to London for an important college interview." Is she trying to get into Oxford or Cambridge? More importantly, might she run into someone she knows while across the pond? Maybe a certain British doctor?
Check out the full synopsis for yourself here:
Equipped with their new information about Mona, the Liars decide they need to speak to Alison. But once the truth is out there, Aria quickly learns that Mike’s involvement with Mona and this new revelation could have serious repercussions for her family. Determined to keep Mike safe and get Ali out of jail, the Liars intensify their search for information on "A".
Meanwhile, Spencer heads to London for an important college interview, and Alison looks to someone surprising for help with her murder trial.
What do you think will go down in Episode 21? Share your theories in the comments below!
Catch the next episode of Pretty Little Liars Season 5 tonight, Tuesday, February 3, 2015 at 8 p.m. ET on ABC Family.
Rebecca Martin is an Associate Editor at Wetpaint Entertainment and our resident Game of Thrones, Pretty Little Liars, and genre TV expert. Follow her on Twitter and Google+!