The story starts off with Finn, Jake, and BMO playing bocce ball. Turtle Princess flies on a hovercraft to meet Lumpy Space Princess at her home in the woods. She finds Lumpy Space Princess fending off "boys" (in this case, ants and fleas) and thinks she is so "attractive" because of her lumps. In order to help Turtle Princess with her boy problems, Lumpy Space Princess vows to write a book to teach her to attract boys with her "turtle lumps." Some of the bocce balls land near the princesses and, upon seeing Finn, Jake, and BMO, and with Turtle Princess's suggestion, Lumpy Space Princess decides to write her book about Finn. She then improvises a dress out a plastic bag from Squeez-E-Mart and leaves for the Tree Fort. For note, Jake and BMO were betting on the winner of the game of bocce ball. Since BMO won, Jake has to call BMO "sensei" for a month.
Upon arriving at the Tree Fort, Lumpy Space Princess uses a fruit pie as makeshift lipstick before knocking on the door. Jake, disgusted, tries to get rid of Lumpy Space Princess but she insists she is there for Finn and Jake's Adventure's Secretary job opening and produces a handmade sign as "proof." Finn and Jake never made a sign, but they could not stand to disappoint Lumpy Space Princess so the duo reluctantly accept her offer and she proceeds to commandeer a table as her desk. Lumpy Space Princess asks for food and Finn looks around for some. Unsatisfied with the options, she tries to "seduce" him in order to make him look for more. Upon "success" in the form of Finn happening upon some leftover spaghetti, she says "Gotcha!" Turtle Princess calls Lumpy Space Princess's phone to ask for an update.
The next day, Lumpy Space Princess finds Finn putting rocks in Jake (who is shaped like a box). Finn and Jake explain they are taking the rocks on an adventure. Lumpy Space Princess insists upon helping them carry some of the rocks. Halfway through the trip, she gets too tired to carry the rocks, and, after dropping them, answers another call from Turtle Princess. After hanging up, the trio reach the top of the mountain they are climbing. Finn begins to throw the rocks into the Loch of Phantoms and explains that Princess Bubblegum told them to use the rocks to find a safe path across. Lumpy Space Princess then tries to seduce Finn by making her dress strap fall off, but it has no effect as he is too focused on finding the path. After finding the path, demarcated by the stones that did not sink to the bottom, they cross the Loch and go into a cave across the way.
Inside the cave, they encounter a portal. Finn and Jake are focused on the portal, but Lumpy Space Princess still tries to seduce the guys by taking off her dress. When this fails, she runs into the portal and becomes trapped on the other side in a chamber full of mirrors. In the chamber, Lumpy Space Princess watches as the mirrors fill with images of Finn. The Mirror Finns take off their shirts and hats, revealing hair down to his waist. The Mirror Finns begin to come out of the mirrors but their bodies are solid black. Lumpy Space Princess panics because she thinks her "powerful lumps" have turned Finn into a monster. Finn and Jake then bust through and defeat the Mirror Finns. After finishing them off, Lumpy Space Princess replies that they came because of her beautiful lumps but Finn insists that what really matters is what is on the inside, "like your brains and stuff." They explain to Lumpy Space Princess that Princess Bubblegum sent them there to destroy the magic mirrors.
Later, as the trio are in the Tree Fort, Lumpy Space Princess notices Finn sitting alone outside. She asks Jake what he is doing out there, and he tells her that Finn likes to go outside and think sometimes after an adventure. Lumpy Space Princess then understands about the lumps on the inside and realizes Finn is the beautiful one with his "inside lumps." Also, it appears that Lumpy Space Princess may have a crush on Finn, shown by a montage of Finn's interactions with Lumpy Space Princess throughout the day. Inspired, she calls Turtle Princess to tell her that her book will be finished soon. A montage plays where Lumpy Space Princess writes her book. When finished, she presents the manuscript to Turtle Princess. Though not what she expected, Turtle Princess loves it and decides to publish and entitle it "I Wrote A Book." Lumpy Space Princess returns to the Tree Fort wearing a brown paper bag and reveals to Finn and Jake that she has been there only to do research on her book. Yelling that Finn is "hot," Lumpy Space Princess flies toward the window in a rush. Jake yells after her, "Lumpy Space Princess, you're wearing garbage for clothes!" While floating out the window backwards, Lumpy Space Princess replies, "Gotcha!" once again saying the title of the episode.
Mentioned or Pictured
- In her writing, Lumpy Space Princess talks about how Finn is a great person who helps her. She also writes that Finn is the hot one, and says his shadow monster was even hotter. Her next paragraph is about how she is observant, and she writes about how Melissa one time had her lumps all crooked when she came out of the bathroom, and she deserved it, because, "that's what you get if you PO Lumpy Space Princess."
- On Lumpy Space Princess's desk there is a binder with a picture of Ricardio on it.
- It is revealed in this episode that Finn now cooks his noodles influenced by Marceline cooking his noodles in What Was Missing.
- It is shown that Lumpy Space Princess eats the fruit pies with the packaging still on it. This is most likely because she has not been eating properly since returning to homelessness.
- In Turtle Princess' library, there are books titled 愛, Romanza, and Amore. These translate to love, romance, and love, from Japanese/Chinese and Italian, respectively.
- The word sensei was used in this episode by BMO, which is a Japanese honorific, literally meaning "teacher" or "master." This may also be related to the fact that BMO speaks in an East Asian accent.
- The scene where Lumpy Space Princess is trapped in a room full of mirrors resembles a scene from Conan the Destroyer.
- The Mirror Finns may be a reference to The Legend of Zelda games where black or dark gray versions of the game's protagonist, Link, are recurring enemies. In one game it is revealed that these "Shadow Links" are created by the Dark Mirror.
- Lumpy Space Princess is seen wearing a bag from Squeez-E-Mart, where Clarence was shown dying in a flashback Jake had during a scene from "Ghost Princess."
- In her book, Lumpy Space Princess writes "Fin & Jake Adventuring Incorporated," misspelling Finn's name. This is exactly the same name that the Business Men wrote on their briefcases in "Business Time."
- Mirror Finn's hair seems almost the same length as the real Finn's hair's first appearance in "To Cut a Woman's Hair."
- It appears that Lumpy Space Princess is still homeless (in "Princess Monster Wife" she was seen living in the woods), even though she returned home in "The Monster." She claims that she did not leave because all the "boys" would not leave her alone.
- When Finn is sitting outside, the flower near him is yellow. But when he runs back inside, the flower is red.
- After Lumpy Space Princess throws a fruit pie at Billy The Vulture, the blue fruit pie in her right hand disappears.
- In the text of Lumpy Space Princess' book, one instance of Finn's name is spelled "Fin."
- Turtle Princess was standing in front of a log next to the tree Lumpy Space Princess uses to keep her stuff, the log is in a different place when they see Finn.
- The table with food that was in front of the bank Lumpy Space Princess was lying down on disappears when she is seen talking on the cell phone to Turtle Princess. Also, when Finn and Jake are there before saying good night to her the oven is not seen next to a washbowl on a table.
- At some point before Lumpy Space Princess answers the cell phone that was on the table when Turtle Princess calls her for the last time, it is pink.
- When Lumpy Space Princess puts her cell phone on the table after Turtle Princess asks her if she is done with the book, she places it face down. In the next scene, however, it is face up.
- In the beginning of the episode, the table Lumpy Space Princess uses is an obtuse angle, but as the episode progresses it turns into a right angle.
- This episode premiered on Natasha Allegri's 26th birthday instead of "Princess Cookie."
This episode was censored in some countries. See Censorship of Adventure Time for more information.