Dr. O'Shay activates Astro by drawing all of the city's power and using it to jolt Astro to life. But the power surge overloads the Metro City Power System, turning Magnamite, the robotic power-controller, into a robotic menace. When Magnamite comes crashing across the city like a huge mechanical octopus, Astro must master his amazing powers quickly in order to save the city from the rampaging robot.

On Deimos, one of the two moons of Mars, robot miners ignore the orders of their human foreman and mysteriously begin digging on their own. Astro must work fast to discover the cause of the robots' strange behavior before Intergalactic Security exterminates them for disobeying.

The evil Skunk tricks Denkou, an "invisible robot," into committing a string of robberies. Astro soon realizes that Denkou is not bad, she just doesn't know the difference between right and wrong -- and Astro is the only one who can teach her.

An experiment in advanced weather technology has turned a desert canyon into fertile farmland, and proven once again that humans and robots can work well together. But a sudden rash of earthquakes and storms threatens to wreck the project. It's up to Astro to find out who is behind the evil plan.

Dr. Tenma builds a powerful robot named Atlas whose abilities rival Astro's. But Atlas has a rebellious nature and begins to destroy Metro City. Astro must save the city from Atlas, while beginning to learn the secrets of his own past.