S.H.A.D.O. was a multi-nation project designed to defend the Earth from invading outer space aliens. Their main headquarters was supervised by Commander Edward Straker (Ed Bishop) who posed as a film producer.

Commander Starker visits with Moon Base Control Personnel

Other S.H.A.D.O. personnel included:

• George Sewell as Col. Alec Freman, second-in-command
• Peter Corden as Capt. Peter Karlin, pilot of the Seagull X-ray
• Gabrielle Drake as Lt. Gay Ellis, of Moon Base Control
• Michael Billington as Col. Paul Foster
• Grant Taylor as General Henderson

The key facilities that supported S.H.A.D.O. were Moon Base Control that was located on the lunar surface, Skydiver, a submarine that roamed the oceans of the world and SID (Space Intruder Detector) which orbited above the Earth monitoring the vastness of outer space for incoming U.F.O. spacecraft. S.H.A.DO. utilized small Interceptor spacecraft that hunted down and destroyed incoming alien crafts.