Who is A.D.? 'Pretty Little Liars' finally answers its running mystery

Brooke Metz | USA TODAY

Game over, PLL fans—we finally know who A is. And she looks pretty familiar.

Pretty Little Liars viewers learned in the series finale Tuesday night that A.D. is Alex Drake — Spencer’s British twin sister.

Yep, just when you thought things couldn’t get any crazier (first we see Melissa in the classic black hoodie, then she rips it off to reveal she’s Mona). Turns out there’s been a Spencer lookalike walking around all these years. And, oh yeah, she’s been impersonating Spencer.

All those cheesy, overly sentimental lines that didn’t really sound like Spencer? That was Alex. That random “one last kiss” for Toby? Alex.

Strangely, it’s actually Jenna, a longtime nemesis of the group, who figures out that “Spencer’s not Spencer.” Her call to Toby after sensing something wasn’t right led him, along with Caleb and the other Liars, to Toby’s old house (which Alex bought). There, Alex had locked Spencer and Ezra in underground rooms -- on Aria and Ezra's wedding day, no less.

But Alex's act is still so convincing that when Spencer and Alex stand side-by-side in front of Toby, he has no idea who to believe. Finally, Spencer's recitation of her favorite poem provides the answer.

Twin insanity aside, the last few moments of the episode — and the show — echo its beginning. After police take Alex into custody, the scene flashes to a sleepover where high school friends, who all resemble each of the Liars in some way, wake up to find two of the girls missing. The last lines are almost identical to lines said by the original Liars in the first season.

“Where’s Addison?” (Or, in the first episode, Alison.)

One of the girls walks in from the yard and echoes Spencer’s lines from the original episode. “She’s gone. I think I heard her scream.”

This game is over, but it looks like Rosewood might have a new A in town.