After a rocket-related mishap, Jimmy Neutron's spazzy pal Sheen Estevez has landed himself on far-off Planet Zeenu. Sounds dangerous, right? Well it is! But believe it or not, it's also the first chance in his whole life that Sheen has ever had to be a hero. On Planet Zeenu he is an Emperor's assistant and a monkey's friend. There are even girls who have crushes on him!