'Pretty Little Liars' Recap: 5 Biggest Shockers From 'The Naked Truth'

Pretty Little Liars: 2/6/12 TV Still - H 2012
Eric McCandless/ABC Family

Did anyone see that coming?

Pretty Little Liars had plenty of action, thanks in large part to the school-sponsored truth event. Among the developments: Jason DiLaurentis is back in town, but he wants answers from the Hastings family. Hanna and Kate are forced to work together at the dance after a compromising photo of Kate makes its way around the school. Aria starts getting suspicious of Holden's secret life.

Here are the five biggest shockers from "The Naked Truth":

[Warning: If you haven't watched Monday's episode, don't go any further. Spoilers ahead.]

1. Spencer and Jason Are Siblings?!: After weeks away, Alison's brother Jason came back to Rosewood and wanted answers from the Hastings family, a reference to the meeting a few episodes back he had with Spencer's father. Turns out, he's the son of Spencer's father. (A flashback to a scene with Alison and Spencer, while Spencer's parents fighting about Melissa and Jason making out in the car.) If that didn't illicit an audible gasp, nothing else this episode will. Now that he and Spencer are tied by blood, it's safe to assume viewers may be seeing a .. softer side to Jason.

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2. Holden's Secret Life Begins to Unravel: After seeing a bag of pills slip out of Holden's bag, Aria begins to grow suspicious of what he's been hiding, thinking that he's either taking drugs or dealing. But does Holden look like the type? Not so sure she's on the ball on this one. Later, she backs away from their pact, saying, that if he's "hurting himself," she can't be a part of it. Oh, and brownie points for saving Aria from Noel, who apparently wasn't attacking Aria when he aggressively grabbed her leg on the ladder, with a swift kick. Maybe he's a ninja?

3. Mona and Emily Try to Outdo Authority: Vice principal Tamborelli passively threatens Emily about telling the truth about the school, saying that maybe the key reason she isn't back on the swim team is because of the way she's been acting. After Mona calls Emily to the vp's office ("I didn't recognize your voice," Emily admits to Mona after hearing her name called on the speaker; "I know, it's a gift," Mona replies). The two find proof of the vp taking bribes, thanks to Mona's sleuthy ways (or is it too convenient?), but Emily doesn't want to blackmail the school. Mona is seen having a not-so-lovely conversation with Tamborelli, helping Emily get back on the school swim team.

4. The Mystery of Alison's Alter-Ego Vivan: The girls discover a slip of paper  with a 215 phone number in the red coat from the drycleaners Spencer picked up after turning in Alison's receipt. On the second attempt, Aria calls the number, with a woman answering saying bluntly there is no Vivian. During the course of the episode, the girls must've forgotten about the phone because by the end, there are six missed calls and as the girls ponder the possibilities, the phone rings again. This time, it's a guy's voice, asking, "What do you want?" The mystery person and Emily make a date to meet.

5. Kate Caught Red-Handed: Kate and Hanna are forced to attend the "Truth Up" event after a naked picture of Kate is sent from Hanna's phone to her contacts list. If it is "A," a clear sign that she/him (them?) is using the girls' phones against them. Hanna discovers that Kate has a birthmark on her body that doesn't show up on the photo that she supposedly sent out; to paraphrase her, Hanna believes someone (i.e. Kate) Photoshopped her head onto a much better-looking body, so maybe it wasn't "A" after all. And voila, Kate admits to her wrongdoing, and because Hanna isn't stupid, Emily and Aria tape the conversation.

Closest Encounters to "A" (maybe): A shadowy figure disappears behind Aria, who is stuck on the roof of the school after she is sent to look for Caleb. And secondly, while everyone's sleeping, "A" takes the laptop out of Caleb's backpack, which leads to next week's Caleb-centric episode.

There is something unsettling about Noel, who continues to take on the villain role, but there is also something slightly off with Mona. Will they continue to factor in? What are your thoughts on the big Jason reveal? Were you surprised? Who wrote "I know who killed Alison DiLaurentis" on the wall? Who was the guy on the phone?

Pretty Little Liars airs Mondays at 8 p.m. on ABC Family.