SHADO engages in its first battle with the enemy. Sky One cripples an alien ship which crash-lands in a lake. Straker's team capture its pilot, a strange blue-skinned humanoid - and the grim secret behind the aliens' are revealed.

"Important? What can be more important than your own son's life?" Straker faces the toughest decision of his career when his son is critically injured in an accident. The drug that can save his life can only be ferried from New York in time aboard a SHADO Transporter - the same Transporter that is in the prime position to track an Alien defector on the West Coast of Ireland.

Straker gets approval from above to build a probe with a camera that will track a UFO back to its home planet. Inexplicably, the Earth technology is capable of following a UFO travelling 8 or 9 times the speed of light and follows it home. The episode ends with a SHADO guy trying to convince Straker that they were wasting their time, even though they picked up some great pictures of the planet.

A UFO imbues three young people with incredible powers. One blows up a radar station, a second steals fingerprints and tries to get aboard a Skydiver sub, blowing it up. The third, a woman, tries to blow up SHADO HQ but the UFO that is feeding her power has now been destroyed.

Foster, whose radio is knocked out and his oxygen line cut, is presumed lost (but they did a crummy job, not even trying to find his body) during a confrontation with a UFO on the moon's surface. Foster is found by an alien, and together, they cross the lunar landscape, developing a friendship when the alien must try to do make-shift repairs on Foster's suit to keep him alive. At the end, a Moonmobile crew finds Foster and misunderstands his intent when he points them to the alien nearby.

After a UFO inexplicably destroys itself less than two miles from Moonbase, a mysterious crystal rock is recovered, and it causes the person in its vicinity to hallucinate. The man on Moonbase who found it thinks Mexican bandits have taken over Moonbase. It gets transferred to Straker's office, and he hallucinates that SHADO is simply a set for a TV series, he is an actor named Mr. Burns, Moonbase can be reached by stepping through two doors from the main control room at SHADO HQ, and "Mr. Straker" is not available. Straker breaks the hallucination by jumping in on the scene while the "character" Gen. Henderson is doing a close-up of the line they were doing when the hallucination began.

Foster is abducted by aliens from a health spa and is being taken out into space, presumably back to the alien homeworld. However, the UFO was damaged and returns to the moon, crashing there. While the Moonbase personnel try to free Foster of the alien environmental suit, Foster wakes up in the steam room at the health spa. The episode begs explanation for how Foster dreamed in such orderly detail, including Carlin missing a shot and Straker angry at the missed shot, and Dr. Jackson's off-line comments to Straker before they go onto a visual link to Moonbase to guide them through removal of Foster's alien helmet.

Foster is suspected of being a security leak, but during the trial, Straker and gang discover that Foster's apartment was bugged and shut down the disreputable business that is selling the spy gear.

After a pilot is killed when Moonbase operatives fail to give him course change information, the personnel are recalled to Earth for an investigation. A UFO crashes in northern Canada and the personnel are assigned to the operation to find the UFO. Gay Ellis is to coordinate the movement of the mobiles trying to approach the UFO.

A flashback episode in which Straker recalls his marriage, followed by stormy days as he must work covertly to get SHADO up and running and recruit personnel. All this leaves his wife angry at his absence, suspicious at the things he might be doing (her father photographs Straker meeting a woman in a parking garage, a woman who will be working at SHADO). In the end, she gives birth to their son.

Freeman takes over temporarily while Straker deals with a woman apparently determined to investigate what SHADO is all about.