Krusty hires Lisa to be his intern, but she’s so good at the job, she ends up replacing him as host of his show; and Bart and Homer discover the world of coin collecting.

Celebrities gather at a posh hotel for the Springfield Showbiz Awards. As a distinguished-looking theater actor addresses the crowd, we hear Sideshow Mel’s voice. Mel narrates this “tale of fame, betrayal, and coin collecting:” the story of how Lisa came to win the coveted Springfield Showbiz Award. In flashback Krusty and actor Drew Carey host Krusty’s 4000th episode, which features three of the original Krusteteers. When Krusty announces that his show is searching for a new Krusteteer, Bart gets excited. He auditions for the Krusteteer role by doing various impressions. Bart loses out to Nelson; whose mother, it turns out, is sleeping with Krusty. Lisa tells Krusty he’s making a big mistake by not hiring Bart. She urges the clown to hire her brother as an intern. The “free intern” idea appeals to Krusty; but he’s so impressed with Lisa’s go-getter attitude that he hires her instead.

A frazzled-looking Lisa tries to keep up with Krusty’s nonstop demands. She begins to fear that she’ll get fired. Sideshow Mel gives Lisa some tips that make her life easier, and urges her to pretend to know who Mitzi Gaynor is whenever Krusty mentions her name. Sideshow Mel’s advice proves enormously helpful. Bart grows increasingly bitter about Lisa’s good fortune. Homer suggests that Bart get rid of everything that reminds him of his hero. Bart gathers up all of his Krusty collectables, and brings them to the Comic Book Guy. He ends up trading them for a book on coin collecting, and a bicentennial quarter. Krusty is greatly impressed when he discovers that Lisa organized his dressing room. He says that Lisa is the best assistant he’s ever had, dubbing her “The Goy Wonder.” Lisa’s star rises when she convinces Krusty it’s in his best interest to put his image on a NASCAR automobile. Bart and Homer focus their energy on filling the slots in the “U.S. Coins” blue book. Bart quickly becomes discouraged, telling Homer the hobby sucks. Homer convinces Bart that the point of having a hobby is killing time. Before long they’ve filled almost every slot in the book. One slot remains unfilled: the “Kissing Lincolns” penny. During the taping of a show, Lisa fills in for Mr. Teeny during a sketch. The audience loves her. Krusty’s agent fears that his client is in big trouble. A short time later Lisa “accidentally” forgets to tell Krusty about a network run-through. Dressed in a clown outfit, she performs Krusty’s monologue. Krusty realizes he’s been replaced by an eight-year-old.

Krusty ends up hosting a late-night cable-access television show. Bart and Homer attend a rare coin auction, hoping to purchase the Kissing Lincoln penny. Mr. Burns outbids them, purchasing the coin for ten million dollars. Homer cons Burns out of the coin by asking him for change for a nickel. Bart and Homer slide the penny into its booklet slot, and pledge to never discuss the hobby again. The scene shifts to Lisa accepting the Springfield Showbiz Award. Sideshow Mel opens a backstage door, and escorts Lisa to the Hall of Winners. On the wall hang portraits of past recipients. Lisa doesn’t recognize any of them; including a portrait of Sideshow Mel. Sideshow Mel explains that “applause is an addiction.” He urges her not to end up like him. He falls to the floor, and sobs. Horrified Lisa races back on stage, and addresses the crowd. She says there’s someone she forgot to thank… and invites Krusty to join her. Before long Krusty has the audience in stitches. Still narrating the tale, Sideshow Mel says that by giving everything away, Lisa kept the only thing that mattered: her dignity. We then see Sideshow Mel in a Krusty sketch, dressed in a fire hydrant costume; with Krusty, dressed as a dog, chasing him.