The Federation of Intergalactic Powers is under threat by gigantic fortress spaceships which have suddenly appeared and destroyed nearby civilization. When conventional defense tactics fail, the Federation looks to find a specially selected person, Hal Bailman and equip him with a special "Lightship". His mission will to be to fly through the defenses of the eight known Air Fortresses and dock at the airlock. Then he must travel through the fortress in only a spacesuit to find and destroy the central core. Once the central core is destroyed, Hal must then quickly find the emergency lightship and escape before the fortress explodes.