The episode begins and Aria and her dad are rehashing the events that took place at the race. He tells her that the school believes they’ve figured out who was behind the horrible prank. Spencer, Hanna, and Emily head back to the school to check out what else was in Harold’s office. Emily and Spencer go in, and as Emily turns to flip on the light they realize that someone else is in the office, and a hooded figure runs out. When they turn the light on the girls see that all of Harold’s things have been cleared out of the office, with only Ali’s journal remaining.
Emily grabs the journal to make a run for it, but Spencer stops her and opens the journal to the marked page, which contains a note from A: “Keep moving ladies. Nothing to see here. – A.”The following morning the ladies are at the cafe discussing their “anxiety dreams,” when Mona walks up. After overhearing their conversation, Mona lets the girls know that she’s been having trouble sleeping as well because Harold has been stalking her. Mona and her parents believe that Harold set fire to the shed thinking Mona was the one inside, and after they spoke with the school administrators about it, Harold was removed from his position. The girls, however, are skeptical of Mona’s story. Later, Lucas tells Hanna that he doesn’t believe she’s cured, and that he tried stopping her and he couldn’t.
And then, it clicks for Hanna. Lucas was the one who locked Meredith in the shed, but he was aiming for Mona. Hanna tells him that if he needs help he can ask her, and he refuses. Emily and Paige make plans to go to a party, but not before Paige gives Emily an earful about the danger they’ve been in, in the past, and how they both need to be more vigilant. At her debate club meeting, Spencer is introduced to a new club member; Mona. As the club moves on to “new business,” it’s announced that Spencer is running for club president against Mona. When the club secretary calls the vote, Mona and Spencer tie which leads to a quiz-off. The quiz-off will take place the following day. As she leaves the building, Spencer receives a text from A: “Quit while you’re head”.
At lunch the following day the girls are speaking about how weird it is that Mona wants to be club president when Mona walks over, thanking Spencer for being “such a sport”. After school Ella is settling in to monitor detention when Meredith sporting a bandaged arm walks into the room. Meredith tells Ella that she saw her and Aria speaking the day before, and that she wants to apologize for jumping to conclusions, and that she hopes she hasn’t made things harder for her and Ella to handle as they’re now co-workers. Ella says she’s sure they can keep things professional. The girls in the meantime are recapping their day when Aria voices her suspicions that her father had something to do with Ali’s murder, and that he intentionally wanted his mom to drink a bit too much that night so she wouldn’t hear him sneak out.
When Aria goes to retrieve the diary pages from their hiding place she realizes they’re missing. Just then, her dad comes in, asking if she’s lost something as the girls are shuffling through the closet. Emily quickly says they were just helping Aria find a shoe, when her dad stops and reminisces, “Remember when your brother used to raid your room for your Halloween candy? You always used to hide it in your snow boots, and he never thought to look there. Pretty clever”. This leaves the girls quite stunned. Lucas has decided that the easiest thing to do is simply leave Rosewood High. He tells Hanna that Mona has been blackmailing him since the masquerade ball and he’s having, to do things ordered by anonymous texts.
When Hanna asks what Mona has on him, he says that he had been selling tests answers to every single test given at the school, and that Mona found out. Over at Aria’s house, Aria hears shouting and when she peeks out the door sees Meredith trying to leave and Byron grabbing her burned arm to stop her, and saying that Aria is his daughter and Meredith can’t just “walk away”. When Aria speaks up and asks her dad what’s going on Meredith leaves and Byron says nothing, before closing Aria’s bedroom door. At the quiz-off Spencer gets the first point. At the cafe, Aria confronts Meredith, saying she followed her there and that she’s never seen her father so angry before.
Meredith invites her to sit down, and tells Aria that her father was angry because Meredith caught Byron in her room going through papers, and that the day prior he had been going through Meredith’s purse thinking it was Aria’s. Meredith tells Aria that when she asked Byron what he was doing he got very defensive, and that when he went to drop Mike off at a friend’s she found the journal pages in Byron’s dresser. Aria grabs the papers, and Meredith tells her that she read them, and she knows that Ali had been blackmailing Byron, because Byron went to see Meredith the night Ali died. At the quiz-off Spencer had been beating Mona, however the score quickly evened out, though Spencer retained a 3 point lead.
The end of round two is announced at the quiz-off, but Spencer declines taking a break. Mona ultimately wins and Spencer is not amused. Andrew offers to “shut this thing down” and go to the faculty advisor to plead their case, but Spencer says she wouldn’t want to win that way. Paige and Emily are walking back to the car when Paige notices a flat tire. Paige kneels down to change the tire while Emily holds a flashlight, when Emily notices that someone slashed the tire. Emily sees a shadowy figure in the woods and begins to chase. When Emily and Paige lose the hoodied figure, they head back to the car and then it’s shown that it’s Toby.
When the girls get back to Emily’s house, Emily apologizes to Paige for putting her in the middle of this and telling her about A in the first place, which has now left Paige completely on edge. Paige tells her not to be sorry, because she feels safer with Emily than with anyone else. Emily then asks Paige to go “see somebody” so that she can try to recover from the A shock. Aria and Meredith arrive back at Aria’s house, and Byron tells Meredith he needs to speak with her. Later that night, Meredith heads into Aria’s room with some tea because Aria’s feeling a little under the weather. Aria sniffs the tea and doesn’t seem to recognize it, and Meredith tells her it’s her “powerhouse blend” that she whips up at the onset of any type of illness.
Meredith offers to take the journal pages back so Byron doesn’t find them in Aria’s room again, but Aria says she’ll hold on to them because she’s hid them again. Meredith and Aria are determined to figure out what Byron’s involvement with Ali’s disappearance was, and as Meredith heads out of the room she pauses to make sure Aria takes another sip of tea. Back at her house, Spencer is chatting with Hanna. Hanna then gets a text from A saying that it was a bad idea to cut Mona off. Spencer asks if she’s certain it isn’t Lucas, and Hanna says it definitely isn’t. Over at Byron’s office, Byron is packing up some papers in the dark. As he leaves, a hooded figure appears from a corner to follow him.
When he steps outside the figure pulls out a cell phone, and it’s shown that it’s Mona. She tells someone on the other end of the phone that he’s leaving, and that she’s going to follow him. Next, a hooded figure is shown creeping through the woods by a train track and laying some masks in the leaves. The episode ends at this point.