Marge takes Bart, Lisa, and Milhouse to the library to study. When they go inside, they realize that the library has removed all the books except for the popular ones. Marge makes the best of this situation by telling stories about history.
King Henry VIII (Homer) is a gluttinous slob who stuffs his face while singing, "I'm Henery the Eighth, I am." When his wife, Queen Margerine of Aragon (Marge), tells him to stop singing, Henry wipes his face with Magna Carta and gripes that Margerine has born him only a daughter (Lisa). That night Henry dreams of a son (Bart Simpson) and strangles him, screaming, "Get out of my dreams and into my wife!"
When Anne Boleyn (Lindsay Naegle) promises to produce a son were she his wife, Margerine intervenes and drags Henry to a marriage counselor (Doctor Hibbert). Henry explains that he wants to marry Anne, but can't execute his wife because her father is the King of Spain. The counselor tells him that while his feelings are valid, marriage is hard work. Henry then threatens to behead the terrified counselor, who quickly reverses his position.
The Lord Chancellor, Sir Thomas More (Ned Flanders), protests that divorce is not permitted in Roman Catholic Church. The King retorts that he will start his own Church. More objects, prompting Henry to promise to "cannon-ize" him in honour of his principles. Sir Thomas is then shot out of a cannon from the roof of Hampton Court.
Henry's new Church divorces him from Margerine (yet still, Henry has to give half of everything to Margerine, which he solves by ripping a map of the British Isles into half, and giving her Ireland) During Henry's wedding to Anne Boleyn, the Archbishop of Canterbury (Reverend Lovejoy) alters the Sign of the Cross by saying, "In the Name of the Henry, the Hank, and the Holy Harry. Amen."
Nine months later, Anne tearfully apologizes to Henry for having borne him another daughter. Henry promises to love their daughter as much as he loves her now. Seconds later, an executioner (Chief Wiggum) beheads Anne on Tower Hill. Henry marries a total of six times, including to Jane Seymour (Miss Springfield) and Catherine Parr (Agnes Skinner). He still fails to produce a male heir, and executes his wives whenever he tires of them.
Finally, in a scene set to the tune of "Greensleeves," Henry is old and sick, lying in his bed with Margerine by his side. He apologizes for having locked her up in a dungeon and asks her to become his Queen again. Margerine accepts tenderly, then violently smothers Henry with a pillow.
Milhouse leaves eagerly to start his school report on Henry VIII, only to be tripped by Nelson, who steals his notes.
Meriwether Lewis (Lenny) and William Clark (Carl) are assigned to explore the West by President Thomas Jefferson (Mayor Quimby). They meet a tribe of Native Americans, whose chief (Homer) offers them the guidance of his daughter, Sacagawea (Lisa), whose name means, "Little know-it-all who won't shut her maizehole." They are accompanied by her husband, Toussaint Charbonneau (Milhouse), until he is slaughtered by Sacagawea's brother Cameahwait (Bart).
Sacagawea gives them many tips on how to survive the land, including how to scare a cougar, but quickly becomes fed up with Lewis and Clark's stupidity. Finally, she leaves them and sets off back home. She encounters a cougar, but before it can attack, Lewis and Clark save her using the advice she gave them. The party arrives at the Pacific Ocean and a heavy downpour begins, prompting Lewis and Clark to name the rain-soaked place Eugene, Oregon. The two explorers reward Sacagawea by creating the Sacagawea dollar which — Marge explains— can be exchanged at the bank for a real dollar.
Wolfgang Amadeus Mozart (Bart) is a big hit in Vienna, playing sonatas on the grand piano. Salieri (Lisa) is resentful of her brother's talents, especially when Mozart wins the award for best composer. At Mozart's flatulence-themed opera, The Musical Fruit, Salieri serves the Emperor (Montgomery Burns) drugged wine. The opera is a success until the foppish audience sees the Emperor asleep and mimics him. Stunned, Mozart declares, "People bored by opera? No way!"
The failure of his opera leads to Mozart's fall from popularity, after which he develops a high fever and becomes deathly ill. At her brother's deathbed, Salieri tells him she wanted to ruin his life, not kill him. Mozart confesses that he thought highly of Salieri's work, believing that it would be remembered more than his — but his youthful death ensures he and his music will be immortalized forever. He then shouts, "Eat my pantaloons", and dies. The next day, Salieri visits the Emperor's court to submit Mozart's Requiem as her own. The Emperor, however, is already focused on Ludwig van Beethoven (Nelson Muntz) and declares all other music obsolete. Crushed, Salieri throws the Requiem away, boards a carriage filled with lunatics, and laughs maniacally as it drives away.
Lisa realizes that Marge's telling of the lives of Mozart and Salieri is clearly based upon the movie Amadeus. She calls the movie completely inaccurate, explaining that Mozart worked hard on his music and that Salieri was a celebrated composer in his own time. Homer recalls that Tom Hulce starred both in Amadeus and in Animal House, and he sings an inaccurate rendition of the Animal House theme over the epilogue.
The episode ends with a facetious epilogue followed by closing credits accompanied by Mozart's Eine kleine Nachtmusik: