Ronny compares Ms. Napier to the infamous torturer Torquemada, believing that she delights in making his life miserable. During lunch, he complains to Jackson about Ms. Napier’s warning that he might repeat seventh grade if he fails math. Jackson is distracted, and Ronny notices Dexter watching him from another table. When Dexter approaches and questions the slogan on Ronny’s T-shirt, Ronny becomes irritated. Dexter inventories the origins of his own old-fashioned clothes in detail. Angry, Ronny storms out, forgetting his tray. He looks back to see Dexter bussing it for him.

Seeking revenge, Ronny retrieves a can of creosote from his shed the next morning and hides it in his backpack. During the bumpy bus ride, he worries that the can will leak. At school, the creosote has leaked slightly, staining his math homework and preventing him from turning it in. After class, Ronny picks the lock on Dexter’s locker with a safety pin, intending to vandalize Dexter’s belongings with the creosote. Inside the locker, he finds a shopping bag containing a T-shirt that says “T-SHIRT,” and he realizes that Dexter was inspired by their conversation to buy himself a T-shirt with a saying on it like the ones Ronny wears. Before he can proceed with his creosote plan, Ms. Napier’s office door opens, and Ronny flees, stashing his backpack in his own locker. The leaking creosote ruins his lunch. In the cafeteria, Dexter offers to share his food, which Ronny accepts. He sees Dexter wearing the new shirt and advises him to open his cardigan. Although he disliked it at first, Ronny reflects that the plain slogan is actually clever.

Gianna is disappointed that her article about the school laminator is buried on the last page, but Traci approves her profile on Dexter. To research it properly, Gianna decides to observe Dexter at The Pines Retirement Village. She follows him off the bus at his stop, surprising him. During a tour of the peaceful community, numerous elderly residents greet Dexter warmly, ask for help with small tasks, and tease him about Gianna being his girlfriend. Gianna observes that Dexter is relaxed and beloved there. They briefly encounter Teagan, who gives Dexter only a cursory nod.

At Dexter’s condo, his grandmother Adele has already prepared banana bread, having heard of Gianna’s arrival through the community grapevine. Gianna sees a photo of Dexter’s parents and learns that they work for the diplomatic corps abroad. Though Dexter has discussed living with them, he prefers The Pines and feels that his grandmother needs him. Gianna reflects on Dexter’s social struggles at school despite his academic success. His only extracurricular is the math team, which a teacher recruited him to join. To avoid upsetting Adele, Gianna says that Dexter is doing great. Adele shares anecdotes about Dexter’s childhood at The Pines, where he became a typical resident, only decades younger. When she expresses happiness that Dexter has made a good friend, Gianna feels sudden guilt, realizing that her friendship is merely a pretense for her article.

In the school library, Gianna shows Dexter the finished draft of her article, which opens with a dramatic story about him rescuing a poodle named Fifi from a storm drain. Angry at the personal details and quotes from his grandmother, Dexter accuses Gianna of spying and tells her not to publish the article. Gianna insists that he can’t block publication and leads him to the newspaper office next to the cafeteria. The eighth-grade staff of the Eyeball give Dexter a standing ovation. The editor, Traci, greets him warmly. An industrial printer churns out copies already containing the story about Dexter. He glares at an unashamed Gianna.

On Wednesday morning, Ms. Napier arrives at school to find students crowding the entrance. Inside, the stairwell is jammed because Dexter is repairing the broken step he tripped on weeks earlier. Two teachers, Mr. Lam and Mrs. Hoffenheim, watch without intervening. Ms. Napier confronts Dexter about liability issues, but he insists that the repair will be solid, as he learned concrete work from a resident named Felix. Ms. Napier and the other teachers clear the crowd as passing students photograph Dexter and encourage him. Though she should stop him, Ms. Napier recognizes his good work and admirable school spirit. She tells him to finish and then report to Principal Dinkins.

In her office, Ms. Napier finds Ronny engrossed in Gianna’s article about Dexter. Ronny hands her a discipline slip about creosote that he found in his locker and complains that Dexter is allowed to do construction while he gets punished. Ms. Napier clarifies that Dexter is not allowed and will also face consequences. After dismissing Ronny, she finds the stairwell empty and the repair complete, with a “Wet Cement” sign posted. As she heads to the principal’s office, she wonders why she is about to punish the one student trying to improve the school.

After school, Dexter tests another code on Leo using an old WWII transmitter nicknamed “Old Bossy.” Leo cracks it in under a minute, decoding a Batman-themed message that Dexter copied from a T-shirt. Though deflated, Dexter listens as Leo explains that codebreaking should be fun and describes how he solved it. Dexter complains about his failed attempt to fit in with his “T-SHIRT” shirt and about Gianna’s article making him look eccentric. Leo laughs and lightens his mood. On the way home, Dexter sees Teagan and her grandparents packing to leave. He feels sad that he and Teagan never reconnected. As the car pulls away, it stops, and Teagan looks out the window at him. When she asks about his shirt, Dexter awkwardly explains his attempt to be cool. Teagan tells him that it looks good on him before the car drives away.

Jackson is irritated that Dexter’s newfound fame from the math team and Gianna’s article is eclipsing his own spotlight. His friends Ronny and Sophie are unsympathetic to his complaints. In science lab, Jackson is partnered with Dexter. Annoyed by Dexter’s presence, Jackson impulsively dumps hydrochloric acid on the back of Dexter’s cardigan. The cardigan begins smoking and then disintegrates and falls off. Panicked, Jackson rushes Dexter out of the lab, claiming a bathroom emergency. He pushes Dexter into a cold shower to wash off any remaining acid and then retrieves replacement clothes—a T-shirt, jeans, and sneakers—from the “lost and found” box. Dexter changes and remarks that he looks like everybody. For the first time, Jackson sees Dexter not as an old man but as a normal, athletic-looking seventh grader. When Dexter says that he likes the new clothes, Jackson is dismayed that he has inadvertently helped his rival become better.

Dexter listens to Leo’s stories about life as a Bunker Boy during WWII. Leo mentions learning auto mechanics to extend his time above ground, which has allowed him to diagnose the school bus as needing a ring and valve job. The next morning, Dexter tells the bus driver, Mr. Milinkovic, who dismisses the concern. Though Dexter has been giving Gianna the silent treatment since her article, he privately admits that it improved his social standing. On the playground, he sees sixth graders playing hopscotch on a shuffleboard court and teaches them the proper game. To find equipment, he leads them into a dusty basement storeroom, where a door swings open, revealing a dark inner room with a collapsed ceiling. Panicked, they quickly leave.

Later, Dexter’s grandmother takes him shopping, where he insists on buying ripped jeans and T-shirts with scientific slogans. Dexter reflects that he considers Jackson a friend, especially after he helped him after the acid incident, while Ronny acts as a volatile frenemy who raids his lunch for desserts. In the cafeteria the next day, Ronny loses money in a vending machine. Dexter uses his Swiss Army knife to open the machine’s back panel to retrieve Ronny’s chips. Patrolman Hagler, the student resource officer, sees him and orders him to drop the weapon. Dexter protests that it's a tool, not a weapon. A crowd gathers, and both Jackson and Gianna tell Dexter that he must follow the school’s no-weapons rule. Under pressure, Dexter surrenders the knife. Principal Dinkins arrives and escorts Dexter from the cafeteria, saying that they will call his grandmother.