Garon, a giant cosmic robot lands on Earth as a meteor, then Astro Boy and the scientists reconstruct him. During a thunderstorm, Garon revives. A corrupt scientist tells Garon to reconstruct an island in the image of his home planet, also changing the atmosphere to match that of the planet, which is toxic to life on Earth.

誤って地球に移送されてきた惑星改造ロボット、ガロンに対して、人類は核攻撃を考える。しかしアトムは別の方法でガロンに対抗する。