Is she ever! In that black hoodie, hair pulled back, she's a Black Swan all her own: Androgynous, feral, all eyes and cheekbones. You'd think pretty little Mona would look silly, like a British person trying to be a ghetto American or something, a cat burglar, but no: She is just simply fucking terrifying.
EN ROUTE TO LOOKOUT POINT
Mona knocks Spencer out, and when she wakes up -- another lacuna -- they're driving somewhere scary. Meanwhile, the Liars lose sight of the Black Swan and decide to get marching orders from Spencer -- which is when somebody figures out that Hanna's new phone -- a gift from Mona, you see -- has been set to record everything, every time she turns it on. Which has got to be hell on a battery, but I guess you'd expect that from some charity burner your best friend gave you.
Mona, verbatim: "I had to get you out there alone, so we could talk... You had to earn it. The right to be a part of it."
Spencer: "Just to clarify, Ali was spying on you in Brookhaven, yes? Or wait, you just made that story up so it doesn't actually matter."
Mona, verbatim: "We're in this together now. I admire you, Spencer. That's why you get to decide how this ends tonight. You can join the A-Team, or you can disappear."
Dumb Spencer ignores all the clues there, even though Mona just totally told her A is a group of persons and that you have to get jumped in and that she's being invited to become part of A, to focus on the fact that Mona is out of her freaking mind bonkers... While answering Hanna's call so the Liars can all hear this conversation. Ha! Sometimes simplest is best.
Spencer: "Uh, you tried to kill Hanna? Me, I get, but Hanna? Aren't you like in love with her?"
Mona, verbatim: "It's easier to forgive an enemy than it is to forgive a friend."
Which is insightful on its own, and I think a fairly deft way to explain Mona's take on all of this, but especially interesting in light of the Black Swan amplification above, because the reason that's true is the same reason I brought it up: You can deal with enemies, with Alison, because you don't let them in. They are not a part of you, but the uglier wider darker universe. But when Hanna hurts you, that's coming from inside -- from your own dark places. Which is always when we do the craziest shit.