"Pretty Little Liars" airs Monday on ABC Family (ABC Family)

In this week’s finale, ‘A’ wasn’t the only one with a hidden identity. 

The tables took a dramatic turn as the girls disguised their faces at a masquerade ball and finally put a face to the mysterious murderer who’s been taunting them. 

At the start of the show, ‘A’ sent another message to the girls in a last attempt to retrieve his (or her…hint, hint) phone. 

“You still have something that belongs to me. Bring it, or one of you leaves in a body bag.” –A 

In an attempt to beat ‘A’ at his own game, the girls continued to search for clues and checked into the motel seen on Allie’s torn postcard, the Lost Woods Resort—such an ironic name, don’t you think? 

While there, the girls discovered Allie’s secret stay in Room 1 just days before she disappeared. 

Meanwhile, Jenna met with ‘A’ and told him that the girls would all be at the masquerade ball that night. Was she helping ‘A’ in his quest to destroy the girls’ lives? What happened to making peace, Jenna? 

Whatever her motives were, Jenna was right. The girls all showed up to the masquerade ball, and while ‘A’ was looking for them, they were also looking for ‘A’. 

It wasn’t until Mona showed up and told Spencer about her meeting with Allison in Brookhaven that ‘A’ would be revealed. 

After convincing Spencer that Allison was watching someone in Brookhaven just days before she died, Mona took her back to the Lost Woods Resort to inspect Room 2. 

Keep your friends close and your enemies closer, right?

Well, that’s what Spencer thought when she went back to the motel that night. 

She concluded that Allie was staying in Room 1 to keep an eye on ‘A’, who was presumably residing in Room 2. 

And she was right. 

Room 2 was more than just a stinky old motel room. It was an evil mastermind’s lair, a sick haven of photographs, costumes, and drawings. 

Spencer was particularly interested in a drawing of a black swan costume. Assuming that ‘A’ was dressing as a black swan for the masquerade ball, Spencer ordered Mona to inform the other girls immediately.

But when none of the girls answered, Spencer realized that Mona had never even called them. Why?

You guessed it. She never called them because she was ‘A’. 

That’s right. Shopaholic, glamorous Mona was a psycho maniac. Crazy, right?

After being arrested and detained for psychological help, Mona received a visit from an unknown person. 

“I’ve done everything you asked me to do,” she said.

Who was this person? Is Mona really ‘A’, or is she simply an accomplice? 

Watch the next season to find out!