When Marge learns Springfield Elementary is the worst school in the state, she and Homer rent an apartment in the upscale Waverly Hills school district so Bart and Lisa can attend a better school. Meanwhile, Homer moves into the rented Waverly Hills apartment and gets used to the bachelor lifestyle.

Krusty grudgingly adds a pretty, singing cohost named Princess Penelope to his show in order to attract more female viewers. Girls love her, and ratings improve, but Bart and Milhouse want to get the show back to the way it was. The situation gets more complicated when Krusty and Penelope fall in love and decide to get married. Meanwhile, Homer, Lenny, and Carl consider working at a competing nuclear plant when Mr. Burns cuts off their daily doughnut service.

When Miss Hoover asks her students to research their family history, Lisa is horrified to discover that most of her ancestors were bad people – a motley crew of horse thieves and deadbeats. But while rummaging through the attic, Lisa happens upon a diary kept by her ancestor, Eliza Simpson. As Eliza’s story unfolds, Lisa learns that her family was part of the Underground Railroad, a group that helped slaves escape to freedom. Eliza recounts liberating a slave named Virgil, but when Lisa presents her findings at school, some of her classmates refute it, leaving Lisa determined to exonerate her family’s name.

When a modernized Springfield Elementary has a technical meltdown, Lisa transforms it into a Waldorf school. Meanwhile, Groundskeeper Willie becomes the coach of the mathletes.