SHADO’s main line of defence within the Earth’s atmosphere is the SkyDiver fleet. The nuclear-powered submarines that SHADO keeps on regular patrol beneath the world’s waters.
The SkyDivers are generally piloted by a crew of five and are serviced at the SHADO naval base on the south coast of England.
Outside the Earth’s atmosphere, SHADO’s main firepower is provided by the Interceptors under the control of Moonbase. These single-seat vertical take-off machines are housed in craters beneath the Moon’s surface and operate in packs of three. In order to destroy UFOs, each Interceptor is equipped with the Earth’s most powerful computer-assisted missile.
A UFO arrives on Earth and collides with General Henderson’s car as he returns from a vacation in America, causing a crash and injuring him. General Calper, who accompanies Straker in a ShadAir jet, takes his place at an International Astrophysical Commission meeting. Calper is hostile to SHADO, but a UFO is spotted homing in on them in flight.
Sky 1 intercepts a UFO and shoots it down over the North Atlantic. The Alien survives and is caught in the net of a new high-tech fishing vessel, where he murders the crew. A signal is sent out, instructing the skipper to make a bomb, in order to lure Skydiver into a trap. The metal fishing net ensnares the skydiver, and the Alien throws an explosive on board. The Alien, however, has forgotten about the skipper, who harpoons the Alien, allowing Carlin to grab the bomb and throw it into the sea before it explodes.
Skydiver gets warned to a UFO approaching their region in the Pacific Ocean. Captain Carlin launches Sky One, but his missile launching system fails as he approaches the UFO, forcing him to rely on cannon fire. Carlin is forced to ditch in the sea after the UFO fires.
On his trimaran Ariel, Robin Jackman leads the ‘Round-The-World’ sailboat race somewhere in the South Pacific, but he loses radio contact with Melbourne 206 days out. When Jackman witnesses a wrecked UFO descending into the sea, he mistakenly believes it is a plane, so he prepares to save the pilot.
After escaping the Skydiver, a UFO lands. Clifton sees this as an opportunity to capture the Mobile in its entirety when it arrives.
However, after he enters the UFO, it self-destructs.