In a magical medieval world, Marge's mother is turned into an Ice Walker and the only way for Homer to afford the cure is to force Lisa to use illegal magic. When the King discovers this, he kidnaps Lisa, and Homer must lead a feudal uprising to save her.
Homer discovers that Maggie is a whistling savant and launches her baby-celebrity career. Meanwhile, Marge impresses Fat Tony with her interior design taste, and he hires her to style his brothel.
Maggie becomes possessed by an ancient demon, Lisa discovers a creepy/perfect version of her family in an alternate universe and Homer cannibalizes himself.
Grampa gets a hearing aid and finally hears what everyone has been saying about him. Meanwhile, Mr. Skinner discovers that his mother has kept the ultimate secret from him.
When Bart goes missing, the town puts together a search party to find him. After most give up hope, Sideshow Bob manipulates Millhouse into revealing where Bart is hiding.
When the Simpsons go to a STEM conference, Lisa falls for a crooning jazz pianist named Brendan. Meanwhile, Bart discovers that he has an affinity for chemistry
Mr. Burns will build a doomsday ark after he believes that the end of the world is near when he sees an old Orson Welles show about Nostradamus. Meanwhile, Professor Frink comes up with a new way of testing everyone in Springfield after Burns wants a test to determine who should go on a spaceship with him.
Everybody is now horrified of clowns after Bart's prank using clown masks, which also causes Krusty to lose his job. He attempts a comeback as a dramatic actor in the play "The Salesman's Bad Day", with Llewellyn Sinclair as his director.
Homer and Marge follow Moe after the bar closes early and discover him and his father fighting. The Simpsons, after finding out that Moe has been excommunicated from his family for years, attempt to bring them back together.
When the Simpsons' flight to Gainesville gets re-routed to New Orleans, Lisa is forced to face her failures, and regain her confidence as a jazz musician. Meanwhile, Bart is intrigued by the voodoo in Louisiana, and Homer is intrigued by the drinking.
Homer gets Flanders a job at the plant, and he soon learns that no good deed goes unpunished when Flanders starts to insist on carpools and demands more from Homer's work performance. Meanwhile, Marge feels as though their marriage has lost its spark.
