As the liars (all five of them!) debated the merits of "...Baby One More Time" Britney versus bald Britney for Hanna's Halloween costume, Noel Kahn pulled up, inviting the girls to his Halloween bash. "Prepare to be scared," he said with a mischievous grin. I think it was a warning to the audience, as well.

Alison went to the costume store to buy her Lady Gaga outfit (which was so ahead of the curve seeing as this was way back in 2008), but some bitch was already eyeing a Mother Monster get-up--Jenna! Her mom had just married Toby's dad, arriving in Rosewood just in time for the holiday. She'd obviously caught plenty of attention already, considering Noel had invited her to his fete. Alison introduced herself and not-so-politely suggested Jenna dress as something else since she was already dressing as Lady G. Her phone then chimed with what could have been the very first text from A, reading, "I'm watching you." We can't know for sure whether it was an A original, seeing as it came from a blocked number and didn't have the usual sign-off, but perhaps this was the first step in the stalker's evolution.

Meanwhile at Hollis, we got our promised "Where's Waldo" moment with Ezra when Aria accidentally bumped into him on the way to her dad's office. She left a note for Byron on his desk, not noticing at first the pretty co-ed luxuriating on his couch. But, she'd definitely notice her later when, in an echo of a previously aired scene, she and Alison spied the two making out in the back of a car. And in the sort of parenting snafu that would make Dr. Spock cringe, Byron asked Aria to keep his secret. Yep, Poor Parenting 101.

Back at home, Alison had a mysterious package delivered to her front door--or at least that's what brother Jason told her as he brought it to her room. Inside, Ali found a voodoo doll with a note reading, "It's my turn to torture you," attached. She took the note and hid it inside a doll she kept stashed in a vent. SO. MANY. CREEPY. DOLLS.

Now, all along we thought the only secret Alison had on Spencer was the fact that she liked to make out with her sister's boyfriends. But not so fast! Apparently, Ali also rigged the class president election so Spencer could win. Or did she? I'm not entirely convinced she actually did anything, but since Spencer can't see through her scheming, she was at once relieved and feeling incredibly guilty over her win. Emily's secret began to come to light, as well. She confessed to Ali that she didn't have sex with BF Ben, like she let them believe when Ben began spreading rumors at school that they had done the deed.

All five later convened at Ali's house to gussy up for the big party, where a masked figure watched them from the lawn. Shudder. Aria only stopped by, however, to say she wouldn't be attending (for reasons only obvious to Ali). Reasons Alison used as blackmail to get her to attend, telling her it was hard securing invites for all of them (especially since Noel Kahn didn't even know her name!).

So the quartet went to the party, where Noel was dressed as a gynecologist (barf) and Jenna was done up as...Lady Gaga! That's right. She didn't heed Ali's advice, turning up in a short, tight red number. Which garnered plenty of attention. Especially from Emily, who quickly (though accidentally) outed herself to Ali. Sensing a queen bee in the making, Ali approached Jenna and invited her into their group, but she turned her down flat. Which, as well all know, would come back to haunt her.

Ali quickly disappeared from the party, worrying the others. Their fears mounted when they all received a text from Alison telling them she needed their help and to come to that crazy-creepy abandoned house in their neighborhood. Feigning a kidnapping, Alison (with the help of Noel who wore the same costume as the peeper) staged an elaborate kidnapping hoax to test the girls' loyalty. They all passed, but not without a lot of quickened pulses and hurt feelings. But when the girls returned to the party, Noel apologized for not making it to the prank. Who was the creepster in costume?

The episode ended on its usual eerie note, with the official debut of A, texting Alison with, "Dying to know who I am? You'll find out."

A few other noteworthy tidbits:

-The detective and Hanna's mom have a history.

-After being bullied by Ali, Lucas turned up at the party wearing the ubiquitous creepy costume.

-Ian tested out his video camera on Alison for the first time.

-Pre-makeover Mona made overtures to be Jenna's friend.

What did you think of last night's "Pretty Little Liars" Halloween special? Who do you think is A? Did Alison come off even meaner than you imagined? And did you find yourself liking Jenna...just a tiny bit? Sound off in the comments and on Twitter!