Bethany climbs out of the book, annoyed to find Owen there, staring in shock. She denies what happened, but her thumb visibly sinks back into the book’s pages as she holds it. When Owen tries to bolt, Bethany realizes that she can’t explain; instead, she drags him into a random book from a floor pile: The War of the Worlds by H. G. Wells.

They land in the Martian invasion of London, sheltering in a gutted building while death rays explode around them. Bethany explains that they’re inside the fictional world and that the story can’t be changed because it’s already written. Owen argues that they should warn the characters about how to defeat the Martians; Bethany refuses and pulls them out, jumping them into Lewis Carroll’s Through the Looking Glass.

In this new book, she tells Owen that she always avoids main characters (and most of the other characters as well) to prevent interfering with the plot. An overwhelmed Owen begs her to confirm the experience is real; she pinches him hard in reply. Back in the library, Bethany demonstrates her ability by pushing her arm into a book and allowing her flesh to dissolve into printed words absorbed by the page. Owen faints.

Owen wakes in the children’s section, fearing that the entire experience was a dream. He arrives at school the next day trembling with the anticipation of talking to Bethany, but she spends the morning pointedly ignoring his glances. At lunch, he follows her to the cafeteria and sits across from her.

Bethany assumes that he wants to blackmail her into stealing something from a book. Owen, thrilled that her comment confirms the experience was real, delivers an earnest argument instead: If fictional worlds exist, then the relentless tedium of daily life isn’t all there is, and that makes everything bearable. Reluctant but resigned, Bethany agrees to meet him at the library that evening to explain her ability, on the condition that he never tells anyone.

While he’s walking home, Owen’s plan takes shape: He will persuade Bethany to bring him into Kiel Gnomenfoot and the End of Everything. The book ends with Dr. Verity pointing a ray gun at the Magister, and he has decided to intervene and save the Magister’s life.

Bethany watches Owen through the library window before going in. She has a stolen Everlasting Gobstopper from Willy Wonka’s factory in her pocket as a bribe for him to leave her alone. At a quiet back table, she offers him the candy in exchange for his silence and absence from her life. Owen refuses, preferring a book visit.

When he asks how she enters books, Bethany reluctantly explains: Her father is a fictional character who somehow escaped his book and married her mother, making her “half-fictional.” At her fourth birthday party, she accidentally pulled herself, the other children, and her father into a fairy-tale book. She got everyone else out, but her father was left behind and has since vanished from that book entirely. Now, Bethany secretly searches for him by jumping into new books each night.

Owen proposes a trade: If she takes him into Kiel Gnomenfoot and the End of Everything, he will show her the Magister’s spell book, which holds a location spell that might find her father. Bethany is tempted but calls it too risky and walks out. At home, she finds her mother tearful over memories of her father, looking into a small hand mirror. After comforting her, Bethany retreats to her room. Her greatest fear is that her father chose not to come back, but she escapes from this thought by jumping into The Little Prince by Antoine de Saint-Exupéry.

At lunch the next day, Owen admits to himself that while a location spell does exist in the Magister’s book, his real motive is to save the Magister. He resolves to confess to Bethany and offer genuine help finding her father. When he approaches where Bethany was sitting, he realizes that she has already gone, leaving a copy of Kiel Gnomenfoot and the End of Everything on the table with a note tucked inside saying “I’m in.”

Owen is instantly overtaken by excitement, imagining himself celebrated as the hero who saved the Magister and became Kiel’s closest companion. He briefly feels that he should come clean but then decides that letting a great wizard die would be the greater wrong. He crumples the note, throws it away, and leaves to make his plans.

That evening, Bethany and Owen sit in his bedroom—packed floor to ceiling with worn-out books that his mother brings home from the library—preparing to enter the book. Bethany establishes five rules: Stay completely silent, never speak to any characters, do not change the story, follow her instructions at all times, and do nothing reckless. Owen challenges the third rule, pointing out that she has previously taken items from fictional settings. Bethany concedes that these were minor, unnoticeable lapses but holds firm.

Owen confirms that the chapter he has chosen for them to enter to access the spell book: Kiel is absent, beyond the edge of the universe retrieving a magical key, and the Magister is absorbed in a spell, leaving his spell book unattended. Bethany reads the passage, and despite her apprehension, she feels an unfamiliar flicker of optimism—that the trip might go smoothly and that Owen might prove to be a genuine friend.

As Bethany begins pulling them into the book, Owen grabs a metal baseball bat from his bedroom floor, thinking he might need it to save the Magister. They arrive in the Magister’s tower study, filled with bubbling potions, caged shadow creatures, and Kiel’s winged cat, Alphonse. The Magister stands motionless, communicating through magic with Kiel, who’s beyond the universe’s edge.

Owen directs Bethany to the large spell book on its pedestal while he stations himself near the door with the bat. The spell book, which senses which spell its user needs, flips on its own to a memory-erasing spell and begins transferring it to her; Bethany backs away before fully absorbing it, refocuses, and finds the location spell.

Seconds later, the door blasts inward as Dr. Verity arrives with a ray gun, destroys the spell book, and levels the weapon at the Magister. Recalling that Verity’s force field is disrupted by solid metal, Owen steps from the shadows and swings the bat, hitting Verity, who drops to the floor. Owen raises the bat and shouts to the book’s unseen readers that the Magister has been saved.

Bethany immediately understands that Owen lied to her; he planned the intervention from the start and used the location spell as a pretext. The Magister, released from his trance, greets them warmly and notes that both visitors carry a strange, unfamiliar quality—not from any world he recognizes. He magically chains Dr. Verity and then remarks that Bethany radiates some kind of power.

The Magister restores his destroyed spell book and uses it to exile Verity permanently from reality, explaining that exile is necessary to prevent Verity’s death from triggering the creation of more clones of him. When Owen carelessly whispers to Bethany about the seventh Kiel book, the Magister overhears the word “book” and begins asking pointed questions.

Bethany tackles Owen and kicks them both out of the story. They crash onto Owen’s bedroom floor. She screams at him, particularly for potentially revealing to a character that he exists inside a book. She then checks the final page of the novel and is relieved to find that their presence wasn’t recorded in the text. She threatens Owen with permanent confinement in a math book if he reveals her secret and then storms out. In her fury, she fails to notice a bright light flashing from Owen’s bedroom window as she leaves.

Finding her mother tearful at home, Bethany leaves to go to the library. Alone in the children’s section, she runs through the words of the location spell, which she can only use once. She’s ready to cast it and find her father but can’t bring herself to do it. The fear that he left willingly and doesn’t want to return stops her cold. Owen’s mother, the librarian, finds her browsing and presses a copy of The Great Brain by John Dennis Fitzgerald into her hands.

Bethany leaves and then realizes that she has walked to Owen’s house without intending to. Telling herself that she’s there to receive a proper apology, she enters through the unlocked front door and speaks to him through his closed bedroom door, laying out exactly how badly he betrayed her. There’s no response. She opens the door to find the room empty and Kiel Gnomenfoot and the End of Everything lying open on the floor. Terrified that Owen has gone back into the story alone, she checks the final page—still unchanged—and then pushes her head in to verify. Something slams into her. As an unseen figure yanks her entirely into the book, the last thing she sees before losing consciousness is Owen’s startled face.