Invaders from the planet Ergdol, which is located in the Earth's orbit, but on the opposite side of the sun, plan to conquer Earth using a small model of the planet at the entrance of the World's Fair.; The Knights encounter alien raiders who want to steal their armor, which was exposed to radiation and turned into the metal that the aliens call Zaxion, which they have used to conquer many planets.; Johnny's grandfather has been telling stories for years about encountering alien invaders during World War I. No one but Johnny actually believes the stories, until the aliens return in the present, and Gran'pa knows how to defeat them.