The kids go on a field trip to the planetarium. Dr. Adams, the guy who runs the place, hypnotizes all the children and tells them all that they love the planetarium and they want to volunteer. All of the children except Cartman, he's snuck out to participate in the Cheesy Poof commercial talent search, where he wins and moves onto the regional competition. An escapee from the planetarium tries to warn about the evils of the planetarium; Mr. Mackey uses a mind meld to get at the meaning of the escapee's message. As usual Stan and Kyle, with Kenny's sacrifice try to get to bottom of the mystery. Meanwhile, Cartman goes to the national competition and wins by default when the other contestants have become volunteers at the planetarium. Of course, so have most of the residents of South Park. He makes the commercial, but winds up saving the day when he gets pissed off and goes to the planetarium because there was no one around to watch his television debut.
Kenny dies when his head explodes because Stan and Kyle were playing with buttons and dials while trying to figure out what makes them like the planetarium so much.