In the Stone Age, ancient counterparts of the Simpsons portray The Invention of Motherhood as Marge tries to keep Homer, Bart, Lisa and Maggie under control.
Moving to the present day, the same things are happening at the Simpson house, and Marge tries to convince Homer to do his chores. In the garage, Lisa finds a rare Morgan car, left by the previous owner of the house and Homer decides to keep it.
In bed later, Marge confesses that she's not happy with her life. Homer seizes an opportunity to cheer her up when he sells Jay Leno his newly found car, and has the money for a trip. However, Leno soon returns and wants his money back, claiming the car wasn't registered to Homer and the police impounded it. Unfortunately, Marge has already decided on a trip to Paris and is very happy. To avoid disappointing her, Homer asks a travel agent if he can get the family to Paris at no cost. The agent offers to have Homer smuggle a package, which he must not to open. On the plane, he opens it, finding a blue snake. Lisa finds out it's a rare endangered species. Homer promises not to let anything bad happen to it, while Lisa promises to help him preserve his marriage. Upon delivering the briefcase at the airport, they find out that the snake would be turned into a belt. Homer and Lisa manage to evade the snake's buyers.
Later, Marge, Bart and Maggie are enjoying a Parisian restaurant, but when Marge finds out about the degree of animal cruelty involved, she asks Bart to dump her pâté in an alley. After putting down the plate, Bart finds out the alley is filled with starving paper-thin models for Paris Fashion Week. Bart proceeds to prank them by making them chase a hot dog on stage, where they get sucked up. Later, when Homer and Lisa try to set the snake free in the gardens of the Louvre, the buyers find them. They chase them to the rue des Lombards, where Homer and Lisa hide in one of the three main jazz clubs, leaving the briefcase behind near a statue. While there, Lisa plays the saxophone when the lead saxophonist collapses. Later in the evening, Homer and Marge go on a stroll and enjoy Paris. Homer confesses to Marge about the snake, retrieving it from the statue, and that he did it to make her happy. They spot the buyers near the river and make a run for it. However, back at the hotel, they are arrested by the police (French Wiggum, Eddie and Lou counterparts) after the contractors called them and having been informed of both Bart's and Lisa's shenanigans. The police search the briefcase and the entire room but find nothing and free the family. After everybody leaves, the snake comes out of its hiding spot in Marge's hair and the family later goes to set the snake free.
The episode ends back at Moe's tavern, where Homer gives Lenny, Carl and Moe gifts from the trip, Moe's gift being a synthetic snakeskin belt. The episode shifts back to the Stone Age, showing a prehistoric Matt Groening drawing and signing the drawing of the scene at Moe's.