Fireball XL5 was part of the fleet of interplanetary rockets protecting Sector 25 of the Solar System from alien invasion under the supervision of the World Space Patrol. In command of XL5 was Steve ...

After intercepting a missile on course for earth, Steve Zodiac and the crew of the XL5 travel to Planet 46 and discover the Subterrains who launch another missile at the earth with Venus trapped ...