The year is 1980 and Earth is under attack from a mysterious race of aliens. Their origins are unknown, their goals unclear. But they are capturing humans to harvest their organs. In a lead lined bunker 80 feet beneath a London film studio, the members of S.H.A.D.O. (Supreme Headquarters Alien Defence Organization) strive to save the otherwise helpless planet. Led by the dedicated Commander Ed Straker, S.H.A.D.O. recruits the finest agents from every nation. From a secret moon base and a fleet of submarine interceptors, they deploy an incredible arsenal of high tech weapons to stop the extra terrestrial invaders.