Around 1970, the British and American governments receive incontrovertible evidence that aliens exist and are abducting humans. In cooperation with the United Nations, they set up a secret worldwide organization, SHADO (Supreme Headquarters Alien Defence Organisation), which operates in the 1980s. With resources and equipment under the seas, in the air, on land, in orbit and on the Moon, SHADO's purpose is to stop the alien incursions and find out why the aliens want humans.
E1
While driving home, Interceptor pilot James Regan and his wife stop for a cat in the road and are abducted by the Aliens. Regan is left behind, and is now being controlled by an Alien mind in the cat. In his Interceptor, Regan is controlled to let a UFO escape and finally places his vehicle on a collision course with Moonbase!
Commander Ed Straker has to make a split-second decision when a lunar module, captained by Frank Craig (David Summer) and with Paul Foster (Michael Billington) aboard, is endangered by an attacking U.F.O. The two men afterwards accuse him of putting them in even greater danger by ordering re-entry at an impossible angle.
Aliens take control of three humans, giving them special powers, and use them to sabotage SHADO.
Colonel Foster goes missing on the surface of the moon and is presumed dead. However, he is still very much alive, and reluctantly joins forces with an alien to survive.
Straker arrives at SHADO headquarters to find a traitor has infiltrated the facility and caused time to stand still.
While at a SHADO spa, Colonel Paul Foster finds himself abducted by aliens, who transform him into a liquid-breather.
Colonel Paul Foster is accused of espionage, leaving the fate of Earth's defences hanging in the balance.
An astronaut's death during an attempt to intercept an alien ship has surprising consequences for those left behind.
Straker recalls how his marriage became strained as he dedicated all of his time to the creation of SHADO.
SHADO mobile units search the countryside to find an alien saucer responsible for one man's death and another's capture.
Straker and Foster are drawn into a bizarre underwater realm where they encounter their exact doubles.
Freeman finds it tough when he takes over from the Commander, while Straker learns that danger comes in many different guises.
A coma victim awakes after 10 years and alerts Straker to an alien bomb hidden on a farm.