Al Gore visits South Park Elementary and talks about the terrible ManBearPig, who roams the Earth and attacks humans. According to Al Gore, ManBearPig is "half man, half bear, half pig". After the boys' basketball game is interrupted by another visit from Al Gore, who is disguised (poorly) as the ManBearPig, Stan says the former American Vice President is just desperate for attention, because he has no friends. Al Gore then phones Stan in the morning when it is still dark, and begins pestering him.
Gore then breaks down on the phone, and Stan reluctantly agrees to go to a meeting, where Al Gore tells Stan and his friends that ManBearPig is hiding in the Cave of the Winds. At first the children are reluctant to go with him; but when he explains that he will excuse the children from school, they agree to go. During the course of this episode, Al Gore repeatedly states "Manbearpig must be stopped!" as well as the phrase "Excelsior!" and "Serial" (meaning serious to him and not to be confused with "Cereal", though the inspiration to him saying "Serial" is that when asked on the Oprah Winfrey Show what his favorite Cereal was, he was mistaking the question for what his favorite Serial [ meaning published or produced in installments, as a novel, film, or television drama] was).
ManBearPigIn the cave, Gore first starts asking illogical questions to the tour guide and begins saying "ManBearPig, ManBearPig, Oink, Growl," trying to call ManBearPig. Al Gore forces the kids to follow him off the path saying "This looks like ManBearPig central" and begins shooting wildly with a SPAS 12 while exclaiming," I've got you now, you son of a bitch!!", causing a cave-in that leaves the kids trapped in the caverns, but allowing Gore to exit the cave safely.
Gore believes ManBearPig caused the cave-in (instead of him) and that he is still at large. While there, the boys search for a way out, and Cartman discovers a small cavern filled with gold coins, pearls, and other treasures. He keeps the others from locating it, and starts swallowing the treasure piece by piece to secretly smuggle it out of the cave.
Meanwhile, a rescue team has been assembled to find the boys, despite Al Gore's pleas that the caves should be filled with molten lead in order to kill ManBearPig regardless of the children. He then diverts the flow of a nearby stream in order to cause a flood that fills the cavern in an attempt to kill the non-existent monster.
The boys meanwhile believe that Cartman, bloated with (fake) gold and jewels, is severely ill, and try to find a way out, carrying him. The cave soon floods (thanks to Gore), and Kyle risks his life to get Cartman to safety. The boys manage to escape just as a memorial service is being held for them, and Al Gore is secretly celebrating the fact he "killed" ManBearPig, and believing he is a hero. Stan accuses Al Gore of using ManBearPig to get attention, but Gore denies this, saying that the man who single-handedly killed ManBearPig is not a loser. Cartman tries to walk away but he does not get far before he begins defecating out part of the treasure.
It is revealed to Cartman that the treasure is fake, used for photo opportunities and is worth "about $14," and Kyle chastises Cartman for making them pull him to safety. While Cartman continues to expel treasure, Al Gore exclaims his intention is to make a film starring himself in which he will try to save the world from something else. He then dons a superhero cape, yelling "Excelsior!" as he tries to fly away.
