The Nightmare Begins

S1, E1: Zim goes to the planet of Conventia for the Great Assigning. It is Zim's greatest wish to be a part of Operation Impending Doom II, Irk's plan to take over the universe. But the Almighty Tallest decides to send him off on a "pretend mission" to get rid of him. The Tallest sticks Zim with a little-known planet called Earth and a less-than-impressive robot named Gir. Together, Zim and Gir head to Earth where they will plot the pathetic planet's destruction. Disguised as a human boy, Zim enters grade school where he passes as a human to everyone but one child, Dib. Although no one will believe that the new kid is an alien, Dib vows to Zim that sooner, or later, he will expose him for the alien that he is.