The Mekon reveals his typically dastardly plan: Earth must submit to his terms or he will propel a hollowed-out asteroid the size of a small planet into Earth. Dan and his sidekick Digby fly to the asteroid in Dan's spaceship, the Anastasia. Arriving at the asteroid they find small buildings and structures and realise it must be inhabited. Digby remains on the ship whilst Dan is lowered down to the asteroid's surface. Once again, Earth is relying on him to defeat the Mekon.
