For the last three season, Mona has been secretly making The PLL's lives a living hell, but now that the doors on her black hoodie-filled closet have been thrown open for all to see, Mona's not trying to hide her hatred any longer.
Titled What Becomes of the Broken-Hearted, the hour sees Spencer continue her long descent into self-destruction and takes her anger out on Mona. But Miss Vanderwaal won't sit back in silence while she's verbally assaulted as you can see in ETonline's sneak peek clip!
And for those of you who think Mona's no match for Spencer in the long run, remember what PLL EP Oliver Goldstick told me: "What's great about Mona is that she's kind of like the bizarro Spencer in some ways. There is no off switch to their brains, and Spencer has a match in Mona so they go toe-to-toe in 3B. It's a lot of fun."
Watch the fun play out above and on Tuesday at 8 p.m. on ABC Family.