Having studied them in his quest to eradicate them, he deduces they are about to start a music festival in South Park, but his attempts to warn the town council fail, and he is arrested soon afterwards for imprisoning 63 hippies in his basement.
A few of them from the University of Colorado Boulder manage to convert Stan, Kyle and Kenny to their cause with talks of corporate evils, and the trio get caught up in the massive hippie crowd where they all listen to jam band music.
After seeing the chaos that the eccentric hippies are creating, the guilt-ridden mayor shoots herself in the head (she survives, and appears later in the strategy room when Cartman is enacting his plan).
Cartman, aided by a scientist (Randy), an engineer (Butters Stotch's mother Linda) and a "black man to sacrifice himself in case anything goes wrong" (Chef), builds a giant drill to bore through the hippie crowd.
The plan works and the hippies disperse, saving South Park, while Stan sees Randy and they end up hugging each other, knowing that they are safe.
Trey Parker and Matt Stone wanted to mix a "really terrible" movie like The Core with music festivals like Burning Man, Bonnaroo, and Woodstock.