The superhero Starman is sent by the Emerald Planet to protect Earth from belligerent aliens from the Sapphire Galaxy. The Sapphireans (or "Spherions") kidnap Dr. Yamanaka and force him to use his spaceship against the Earth.
An evil brain from outer space unleashes monsters with deadly diseases on Earth with trying to conquer the universe. Superhero Starman must battle them all to save his planet.
