After learning he has narcolepsy, Homer gets drunk instead of going home with his medicine; a visit to a marriage counselor leads to a trial separation for Homer and Marge; Homer dates a woman in her 20s.
Bart and Lisa are on the case when someone steals the smoker Homer bought from a mysterious man at a barbecue shack.
Selma and Patty agree to stop smoking when they learn their father died of lung cancer; when Selma relapses, Patty becomes angry and moves in with Homer and Marge.
Homer and Lisa hide in the attic while former Halloween pop-up employees -- angry at Homer who cost them their jobs -- invade the Simpson's home.
Sideshow Bob kills Bart; Homer has short-term memory loss; radiation exposure gives Lisa, Bart and Milhouse superpowers.
Lisa makes a new friend named Harper (Kristen Bell), who comes from a wealthy family; Homer befriends Harper's dad and enjoys the benefits of having a rich pal.
When Homer loses $5,000 to Broadway legend Laney Fontaine in a poker game, he settles the debt by loaning out Lisa for a month; Laney transforms Lisa into a show-biz kid.
Lisa tries to restore the reputation of Springfield's first female inventor; Bart tells a lie that causes Homer and Marge to believe he is a sociopath.
The story of Bart's life from 6 years old to his time as a young man reveals that Lisa's achievements and his relationship with Homer have shaped him more than he realized.
After Homer is fired, he returns to his favorite job -- a dishwasher at a Greek restaurant; Lisa accidentally creates sentient artificial intelligence.
Bart is captivated by a new teacher (Sofia Vergara); Homer buys a new brand of what he thinks is milk, which causes early puberty for Bart and Lisa.
Sanjay gives his stake in the Kwik-E-Mart to his son, who turns it into a trendy health food market; Bart decides to take the new store down.
Professor Frink uses science to transform himself into a more attractive man; when Marge, Bart, and Lisa visit Grampa for Valentine's Day, they find the old folks in a drug-induced hallucination that lets them relive happy memories.
Bart lets a homeless woman live in his closet after he accidentally loses her cart in the river; when Homer tries to prove that he is handy, he mistakenly traps the cat in the walls.
Lisa becomes an intern at the local veterinarian's office; Marge works as a crime scene cleaner to earn extra money, but has a difficult time with the gore.
After failing to talk Lisa out of volunteering for a one-way journey to Mars, Marge decides to go with her.
Homer tries to find a boyfriend for Smithers, who is crushed by Burns' lack of affection; Milhouse replaces the lead in the school production of "Casablanca" when Bart takes the boy out.
When Marge takes Lisa to Capital City for a musical, the star tells Lisa how lucky she is to have a great mom; Bart comes up with a new plan to trick people.
Homer recalls a family vacation to the Grand Canyon with the Flanders.
Homer makes a deal with a travel agent to be the courier of a top secret briefcase to get a discount on a family vacation to Paris.
Homer embarrasses himself while trying to read a speech at work, then turns to improv comedy to regain his confidence for public speaking; Marge decides to rebuild Bart's treehouse.