Homer is cast as the lead in Everyman, a super hero movie written by Comic Book Guy. But the newly christened actor has trouble staying on the exercise and diet regimen that his provided fitness trainer lays out for him.
After Mrs. Krabappel confiscates her class's cellphones, Bart spikes Krabappel's coffee with liquor, which lands her in trouble with Principal Skinner.
The men and boys of Springfield become obsessed with Mixed Martial Arts, a unhappy sport where fighters inflict severe pain on one another. When Marge and her friends stage a protest, the show's promoter embraces the controversy and challenges Marge to a match, promising to shut down the competition if she wins.
This year's triple threat of Halloween hilarity sees Moe using Homer's blood for beer, Bart and Lisa caught in a hug pact, and everyone in Springfield becoming zombies thanks to Krusty Burger's latest sandwich.
Marge poses for a calendar for charity, but she is soon the talk of the town after she reveals a little too much during her photo shoot.
Principal Skinner tells Bart about Andy Hamilton, a former student who was an even better prankster than Bart is. Bart tracks down Andy, now 19 and still pulling pranks, and the two become quick friends.
Lisa decides to walk through the field after getting lost in a game of hide-and-seek, but she discovers three teenage girls who are practicing Wiccans instead. Although Lisa doesn't believe in their spells, the girls convince Lisa into understanding that they never hurt anyone and they ask her to join. However, Chief Wiggum arrives before Lisa is inducted, and Lisa becomes the star witness in the case of the three girls' arrests. Meanwhile, after discovering that they make moonshine, Homer begins hanging out with Cleatus and his hillbilly friends.
After Lisa informs Bart that she and Maggie have a special bond that he'll never know because he doesn't have a brother, he takes a trip to the orphanage to find out what he's been missing out on.
After Grampa meets Marshall Goldman and Mitch Albom and start telling about the time he was on a World War II battleship, the article gets published in the Springfield Shopper. However, Homer becomes so jealous of Grampa's newfound fame and seeks a surrogate father, only to find out later that there is a draft on Goldman's third column, which could have terrible results for Grampa.
In the landmark 450th episode of The Simpsons, Krusty the Clown gets a female costar, Princess Penelope, on the show. However, he falls in love with her and proposes a marriage. Meanwhile, the workers clash with Mr. Burns at the nuclear power plant.
Homer blows off Marge to buy a lottery ticket and winds up winning the million-dollar jackpot. Fearing how Marge will react if she finds out the reason Homer missed their date, Homer keeps his newly inherited fortune a secret and spoils his family with "anonymous" gifts. When Bart finds out, he and Homer spend the money like it's going out of style, including buying front-row to tickets to see Coldplay in concert.
Homer takes Marge out for a romantic evening of ice skating and hand-holding, but upon entering the rink, they encounter a curling team practicing. Marge and Homer take to the ice and discover their love for the sport, and soon after, join the curling team and compete with them in the Olympic trials. Team Springfield claims the win and moves on to the 2010 Vancouver Games where Bob Costas covers the action. Meanwhile, sleazy vendors introduce Lisa to the world of collecting Olympic pins, and before long, Lisa is hopelessly addicted.
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 Bart fails to turn in his homework, Mrs. Krabappel sends a letter home about Bart's behavior. Despite Bart's best efforts to intercept it, Homer reads the letter, and he and Marge visit Principal Skinner for a parent-teacher conference. Furious, Homer punishes him, but Marge takes a more sympathetic approach. When Bart realizes he can pit Homer and Marge against each other to his benefit, his scheming reaches new heights.
Principal Skinner announces that Mrs. Krabappel was called out of town and budget cuts dictate that, until she returns, the school's two fourth grade classes will merge. Bart reluctantly shares a desk with Nikki and develops a flirtatious rapport. Bart talks to Grampa about his new crush, and at Grampa's suggestion, gives Nikki a kiss. But when Nikki starts sending Bart mixed signals, he swears off women forever. Meanwhile, Lisa's classmates ostracize her for being an overachiever, and First Lady Michelle Obama, a self-professed nerd, comes to Lisa's defense.
When The Simpsons go to the Holy Land, Homer is convinced that he is the Messiah. This winds him up in a lot of trouble as the Muslims, the Jews and the Christians all decide to work together to teach Homer a valuable lesson.
Smithers is placed in charge of the power plant after Mr. Burns is thrown in jail for possession of stolen artwork. But the plant employees work together to get Mr. Burns out of jail when Smithers abuses his powers as boss.
Homer is completing his court-ordered community service when he befriends his supervisor, Chief Wiggum, by offering him one of his sandwiches.
Touched by the act of kindness, Wiggum assigns the other convicts unpleasant tasks, but allows Homer to join him at the picnic table.
They continue to grow close, but when the Chief gets injured during a botched bank robbery, Homer doesn't come through when Wiggum needs him the most.
Meanwhile, Bart becomes addicted to Battle Ball, a Japanese game made up of plastic balls and magnetic cards, and his family and teachers try to help him kick the habit.
The Simpsons decide to embrace a cheaper, alternate source of energy by erecting a wind turbine in their backyard.
But when Homer realizes some of the power is being directed to the local electric company, he decides to remove his home from the grid and becomes completely dependent upon an unreliable source of power.
Meanwhile, a storm erupts, trapping a magnificent 150-foot-long blue whale ashore, and Lisa and Homer attempt to help the poor creature.
A bomb squad mistakenly blows up Homer's unattended gym bag, releasing radiation into the city and authorities react by suspending civil liberties.
Wiggum and his men install surveillance cameras around Springfield and round up suspected terrorists, including groundskeeper Willie, but when monitoring the nonstop flow of video imagery proves to be too much, Wiggum enlists concerned citizens to help keep the city safe.
As Mother's Day approaches, Moe narrates an episode in which he writes a letter to Homer, Apu and Reverend Lovejoy, who are vacationing with their children, and threatens to run away with one of their wives.
While the trio tries to determine whose wife Moe is referring to, Homer, Lovejoy and Apu flashback to the intimate moments they initially ignored between Moe and Marge, Manjula and Helen Lovejoy.
But when the boys return from their trip, they're in for the surprise of their lives.
Bart believes his new neighbor Walt is Sideshow Bob in disguise, returning for revenge.
When Moe discovers a hidden talent for judging contests, he is approached by a television agent to join the AMERICAN IDOL judges panel.