|“||I know you're still "A"||”|
— Hanna to Mona
Aria is watching an old movie when Byron tells Aria that the principal believes they've figured out who caused the explosion. When he leaves he mentions that he has, in fact, seen the movie she is watching and that one of the characters keeps a severed head in a hat box. She is still furious with him and doesn't trust what he says. Spencer, Hanna and Emily go to Harold's office looking for the diary. Spencer hears something, and a person in a hooded sweatshirt suddenly pops out and escapes from the office, but not before Hanna catches sight of their dirty, black shoes. They find the room empty of Mona's things and a diary that looks like Ali's, but does not have writing in it. All is left is a note from A that reads: "Keep moving, ladies. Nothing to see here."
All the girls discuss the latest events over coffee. Aria is having Ezra and Byron troubles. Spencer is running unopposed for the open position of captain of the Academic Decathlon team, as the captain had gotten in a bike accident. Mona walks over and tells them that she thinks Harold is stalking her. She tells them that she met Harold while she was at the Lost Woods Resort, and they had a few conversations, but Harold wanted to have a relationship with her. Mona rejected him and he later followed her to the school where he bribed the regular janitor to take over his job. She thinks that Harold caused the fire at the marathon, and that the police are searching for him now. After she leaves, Hanna tells them she thinks there is "more to the story." Hanna tells Lucas that she knows that it was him in Harold's office last night, and he admits that he was looking for something. He also admits to setting off the explosion as a way to scare Mona. She offers him help, but he says that there is nothing she can do.
Paige tells Emily her parents are being very strict and setting curfews for her since the lighthouse catastrophe. However Emily wants to go to a swim team party being held in the woods, and says that they'll just arrive and leave early. Aria talks to Ella about the night Ali died. Ella tells Aria that she and Byron had gone to a barbecue at Hollis after they dropped Aria off at Spencer's. They had left the party early and sat on the porch at their house to drink wine. Ella reveals that she had too many glasses of wine that night and could have slept through a stampede. Spencer learns that Mona is joining the Academic Decathlon. Spencer isn't pleased. Mona is also running for team captain as a way to "show people who I really am." The first vote is a tie and Mona calls for a quiz-off the following day. On her way out of the meeting Spencer gets a text from "A": "Quit while you're ahead bitch."
Spencer talks to the girls about "A" trying to scare her off the decathlon team. Mona walks over and thanks Spencer for being such a good sport. She also tells the girls that while she isn't allowed to use a phone, the principal let her have limited access to the computer lab with supervision, for homework only. That was how she had posted the apology video, with Jason as the supervisor. Hanna asks how are they to believe anything she says when they knew she had snuck in and out of Radley, and Mona tearfully walks away. Meredith talks to Ella about the explosion. She says she jumped to a conclusion about the girls. Aria tells Hanna and Emily about her mother's version of what happened the night of Ali's death. She wonders if Byron intentionally got her drunk to sneak out of the house. Emily says that in the journal entry, Byron had promised to meet Ali after she came back from her grandma's, which was the night she died. Aria disagrees and says that maybe he agreed to meet her at a different time, and goes to get the diary pages. Aria can't find them, which she hid in one of her boots. Byron pops his head in and makes a reference to Aria's clever way of hiding things in her boots. He leaves, and Aria says, "He knows."
Toby helps Spencer cram for the quiz off. Spencer tells him the only way to stop Mona from baiting her is to beat her. Toby won't be there because he has to have "dinner with his boss", who calls him at that moment. Toby says he'll be straight over. Hanna drops by Lucas' house to make sure he's okay. He says he's leaving Rosewood, "for good." Lucas says Mona has been blackmailing him since the masquerade ball for selling the answers to all the tests at school. When he told her he was done doing things for her, someone tried to run him over in an SUV. He believes it was Mona, but as revealed in "She's Better Now," it was actually Toby. Aria overhears Byron and Meredith argue about Byron sneaking around in Aria's room and rummaging through her things. During their argument he grabs her injured arm rather firmly. On the way to the party Paige tells Emily she needs to pull over. She seems to be having a panic attack of some kind. Paige says she "can't to anything" since Halloween. Her parents don't actually have her on restriction, she says; she's just too terrified herself to leave her house. The death of Garrett has her worried about the next bad thing that might happen.
Spencer and Mona begin their quiz off. Spencer starts off strong. Aria follows Meredith to a coffee shop and asks if there's something she should know about based on how angry her father was. Meredith says she caught Byron rifling through papers in Aria's room. The day before, he was going through her purse because he thought it was Aria's. She found the diary pages in Byron's drawer. Meredith says he came to see her the Alison's disappearance. Byron left her apartment that night to go meet Alison. Spencer continues to maintain a lead over Mona. Paige and Emily return to Paige's car and finds one of the tires has been slashed. They see somebody in the trees wearing a black hoodie, and Emily takes off after them. Emily loses track of the person and Paige convinces her to return to the car. After they leave, the black-hooded "A" is revealed to be Toby. After two rounds, Spencer holds a three point lead over Mona. The two are offered a break, which Mona seems to need. But Spencer decides to keep going. Spencer chokes on a question that would win the game. Mona takes over and gets it right, becoming the captain of the team.
Byron is waiting for Aria and Meredith when they come home. Byron apologizes to Aria for scaring her. Spencer tells Hanna she lost to Mona and needs to get out of there. Hanna walks over to Mona and tells her that she knows she's still pulling strings and manipulating people. Hanna heatedly says that she wants nothing to do with Mona, who says, "I'm sorry you feel that way." Hanna gets a text from "A" that says that cutting Mona off is a "big mistake." Spencer thinks Mona won the quiz battle by intentionally showing her a weak spot on purpose, causing Spencer to act cocky and underestimate her. With Paige's car out of commission, Emily crashes at Paige's place. Paige is amazed that Emily could be so brave. Emily wants her to get professional help. Aria is getting sick and Meredith brings her some tea. Aria has hidden the diary pages again. Meredith asks Aria if she thinks her father could intentionally hurt Alison. With Byron out of town Meredith wants them to take the next few days and figure out what to do. A hooded Mona reports to someone that "he's leaving. I'll call you back." This reveals that Mona does in fact have access to a phone, and could've sent those texts to Spencer and Hanna.
"A" is shown running out into the woods, and burying the Queen of Hearts mask and the mask Mona wore to look like Caleb from the Halloween train under the leaves.
- First appearance of Andrew Campbell, who was a love interest of Spencer's in the book series.
- It is revealed that Lucas started the explosion in She's Better Now to hurt Mona.
- It is also revealed that Lucas was the one that got in a skateboarding accident in the beginning of the previous episode, but he assumes that the driver who was chasing him down was Mona.
- It is revealed that Lucas is part of The A-Team due to blackmail.
- The title is most definitely a reference to Mona Vanderwaal.
- May reference the disease monomania, a form of partial insanity conceived as single pathological preoccupation in an otherwise sound mind.
- "Losing Ground" by Trent Dabbs
- "Tightrope" by Felicia Barton
- "Grow" by Neulore
- "Scared of Me" by Fedde le Grande
- "Down the Drain" by James Cappra Jr.
Mona-Mania has a photo gallery.
- Troian Bellisario as Spencer Hastings
- Janel Parrish as Mona Vanderwaal
- Ashley Benson as Hanna Marin
- Lucy Hale as Aria Montgomery
- Shay Mitchell as Emily Fields
- Chad Lowe as Byron Montgomery
- Brandon W. Jones as Andrew Campbell
- Keegan Allen as Toby Cavanaugh
- Holly Marie Combs as Ella Montgomery
- Brendan Robinson as Lucas Gottesman
- Amanda Schull as Meredith Sorenson
- Lindsey Shaw as Paige McCullers