Bart is stuck in a rut, doing the same day-to-day all the time. But on TV, like what happens a lot on the show, a solution appears; in this case, an ad for a cruise line. Bart begs for the family to go, but finds out they can't afford it. Even after selling all of his things (including all future meals to Homer), he is only two-thirds of the way there. Taking pity on Bart's problem, Lisa sells her rare jazz records; Marge sells her fine china (which her own mother stole when she was working as a cleaning lady); and they sell Homer's mini pool table (without telling Homer) and have enough cash to fill the jar the rest of the way. Homer complains about (all the way to the ship, in fact) how family vacations are only fun for the kids, well the parents still have to work instead of relaxing. When they get to port, the family is informed that the economy room they got was over booked, so they get an upgrade (followed by a double and triple upgrade). Bart is happy to know that now the family is on the perfect trip.
It goes well for the family. Homer and Marge get the suite to themselves, allowing them to 'snuggle' with the help of the motion of the ocean; Lisa is with the "KidZone Elite," a place where all of high-class kids doing stuff not too different from Mensa; and Bart enjoys of the activities on the ship, from Lazer Tag to a lecture on the history of cruise ships. Bart joins his family for dinner and the ship's activity director, Rowan Priddis, sings a song that reminds Bart that the fun only lasts a week. Not wanting to go back to his boring life, Bart plays the movie "Pandora Strain" from the suite on the screens, making everyone think there is an outbreak keeping all ships at sea. And to keep the crew from contacting the land, pours hot fudge from the sundae bar on the ship's radio. Bart enjoys the eternal vacation while everyone else panics.
Days later, the ship becomes something similar to a movie like Mad Max (ironic because this was started by a movie). Rowan Priddis plans to have the survivors on ship to settle in Antarctica to start mankind anew. The stand-up comedian questions why he spent so much time nit-picking, the fitness centre has been taken over by a cult led by a lifeguard (claiming that the pandemic was caused by man running on deck), and the buffet food has long ran out, replaced by seagull, barnacles, and jellyfish. Bart is noticing that the family is not enjoying this as much as he is. Marge and Homer are too worried to be in love; Lisa and the Kidz Zone Elite are like monks in the Dark Ages, writing down the records for future generations. Bart gets into hot water, however when the family finds out about the movie and makes him confess. Treat Williams, who played the general in the movie, says that he 'thought that guy look familiar.' Everyone is upset at, not just Bart, but the whole Simpson clan for putting them through this (one man even claiming to have possibly eating people meat, which Bart finds disturbing). Marge tries to using the biblical quote of "Don't judge, lest ye be judged," but the Simpson clan is left behind in Antarctica, anyway.
The family is angry at Bart, calling him selfish. Bart explains that he did it for the family too, claiming that they were happier then they were back home. On the way to a research station to take them home, they find a rookery of penguins. When Bart makes an example of how life is not fun most of the time, Lisa points out that well life is not perfect, one should just enjoy perfect moments when they happen. They belly-silde down the hill with the penguins, with Bart knowing it will be one of many cherished memories.