Disappointed over a new episode of Itchy & Scratchy (where Itchy listlessly hits Scratchy with a mallet four times and it ends with a tacked-on "Say No to Drugs" message), Bart and Lisa decide to write their own episode. Inspired by Homer accidentally cutting Marge's hair off with hedge shears, they write "Little Barbershop of Horrors" and send it to Roger Meyers Jr., complete with cover letter. Roger barely looks at the letter and script as he's too busy bullying and abusing the Harvard-educated writer (who looks like real-life Simpsons writer, Jon Vitti) he just fired for doing subpar work.
Correctly guessing that Meyers did not take them seriously because they were children, Bart and Lisa resubmit the script under Grampa's real name, "Abraham Simpson," which Grampa finds in his underwear. Meyers loves the script and hires Grampa as a staff writer (but only after Roger Meyers' secretary calls him about where to send the check he received for "his" script and Grampa meets Roger Meyers, Jr. in person and demands another check). Grampa comes by and tells Homer that he's getting paid $800 a week to "...tell a cat and mouse what to do," which makes Homer immediately think that Grampa's senility has finally gotten to him. Bart and Lisa inform Grampa of their scheme, and the trio conspire to continue passing off Bart and Lisa's scripts as Grampa's, splitting the money three ways. Bart and Lisa's cartoons are met with acclaim from audiences, resulting in Meyers firing Itchy & Scratchy's entire writing staff except for Grampa, who freaks out over being outed as a fraud, though Meyers doesn't notice or care about Grampa's confession.
Meanwhile, Homer and Marge attend their "Class of 1974" high school reunion (where Marge's prom date, Artie Ziff, is now a multimillionaire, but still pines for her, with Homer seriously considering renting her to Artie out for one night, a la Indecent Proposal). Homer and Marge have a great time and Homer wins a variety of humorous awards, like "Most Improved Odor" or "Gained the Most Weight". However, Principal Dondelinger interrupts the ceremony to announce that Homer technically never graduated from high school due to failing a remedial science course (even though Homer already knew he flunked out of high school and told Marge about it when she discovered that there was no invitation to the reunion for Homer) and revokes all of Homer's awards. Determined to win back the accolades, Homer retakes the course and passes the final exam, finally graduating.
For "his" work on Itchy & Scratchy, Grampa is nominated for an award for Outstanding Writing In An Animated Series, alongside the wedding episode of Strongdar: Master of Akom, the "how to buy Action Figure Man" episode of Action Figure Man, and the season premiere of Nickelodeon's The Ren and Stimpy Show (shown as a slide that reads, "Clip Not Done Yet" due to that show's notorious production delays under showrunner John Kricfalusi). When Grampa sees Itchy & Scratchy for the first time in a clip show introducing the award's nominees, he is appalled at the violent and gory humor. Grampa wins the award, but in his acceptance speech, he condemns the cartoon's violence and the viewers who enjoy it. Grampa storms off the stage as the audience boos and pelts him with fruits and vegetables, though two writers (who look like Al Jean and Mike Reiss) take his message to heart and give up cartoon writing (with the Al Jean writer declaring that he's going to write a live-action sitcom about a sassy robot). Grampa gives the award to Bart and Lisa, and Bart declares he will never watch an award show again, "unless that delightful Billy Crystal is involved".
The episode ends with an elderly Homer and Marge attending the 50th reunion in 2024, and Homer humiliating himself again by appearing with a plunger stuck to his head.
Before the rest of the credits start to roll, a brief segment entitled "The Adventures of Ned Flanders" is shown (complete with its own theme song). In it, Ned scolds Rod and Todd for not wanting to go to church. They then tell him that it is in fact Saturday, and Ned laughs as the episode finishes completely.
