Zim dreams of greatness. Unfortunately, he is hopelessly inept as a space invader. Desperate to rid themselves of the annoying Zim, his planet's leaders send him on a mission to infiltrate Earth, equipping him with leftover, makeshift gear. To their dismay, Zim successfully establishes a base on Earth and integrates into human culture, posing as a human child while plotting the planet's downfall. Only Zim's archnemesis, Dib, realizes that Zim is an alien, and of course, nobody believes Dib's claims.