Invader ZIM, a puny green soldier from planet Irk, gets banished from the Irken Empire after single-handedly botching their first invasion effort. After begging his superiors, the Almighty Tallest, for another chance, they decide to get rid of him once and for all. They trick him into going on a "secret mission" to an obscure planet at the edge of the universe, a planet with the unlikely name of Earth. Intent on bringing down the human race and proving to his superiors his worth, ZIM roams the planet, disguised as a schoolboy, in search for the planet's weaknesses. The only one standing in the way of ZIM's mission is his classmate Dib, an obsessed paramormal investigator, tries to unveil his true alien identity. Will ZIM destroy the planet Earth before DIB proves his secret to all humankind?