Pretty Little Liars Pretty Little Liars

[WARNING: The following story reveals the identity of Pretty Little Liars' A. Read at your own risk].

The mystery of A's identity in ABC Family's Pretty Little Liars has finally been revealed and ultimately mirrored the books on which the series is based.

In the Season 2 finale, Spencer, Hanna, Aria and Emily grew closer to uncovering A by discovering a seedy motel that Alison, their murdered friend, had visited. It was the group's brainiac Spencer who realized that A wasn't following Alison; instead, Alison was spying on A, whose lair was in Room 2 of the Lost Woods Resort. Spencer took Mona with her to sneak into the room. Upon opening up a diary that was bookmarked with a gum wrapper, Spencer figured out who exactly that wrapper belonged to — the gum-chewing Mona.

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But could Mona be working alone? Of course not. As Mona told Spencer, "You can join the A team or you can disappear." So who's helping her out? Earlier in the night a girl in a Black Swan costume, drawings of which were found in A's room, was seen talking to Jenna and Lucas — both of whom have motive to be on Mona's side. And then there's Melissa, who threatened the girls earlier in the episode and whose favorite game to play with her sister Spencer was hide-and-seek, the same game written on the PLLs' invitation to the Masquerade Ball.

Ultimately, Mona was locked up. Dr. Sullivan, who returned to Rosewood after being threatened by A earlier this season, explained Mona's condition. "She was living in a perpetual state of hyper reality," Dr. Sullivan tells the girls. "The adrenaline rush that accompanied her feelings of empowerment fueled Mona's ability to be seemingly all-knowing and omnipresent."

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And as for Mona, she may be behind bars, but her team is still out there. "They think it's over," she says in a voiceover. "Loser Mona is going to the nuthouse, and those precious liars are going to sleep at home with their windows open and their doors unlocked.  Don't they know that's what we want?"

But is Mona really A? In the final scene, she's accompanied by a visitor in a red coat. "I did everything you asked me to," Mona says to the mysterious person.

What did you think of the Pretty Little Liars finale? Comment below!