A mysterious comet is revealed to be heading towards South Park Colorado. Cartman, Kyle, Stan, and Kenny must try to stop it before it lands and kill the various evil forces it has spawned! Mutant turkeys, killer cows, "Visitors", giant clones, living toys and robots are among the many evil minions and enemies that have flocked to South Park because of the comet. Their only help are various weapons and Chef who gives them advice.