'Survival' originally transmitted on ITV (ATV Midlands) 6 January 1971
Written by Tony Barwick, Directed by Alan Perry

A UFO lands undetected near SHADO's moonbase. An alien sniper disembarks and shoots a window in one of the moonbase's spheres. The resulting decompression suffocates astronaut William Grant, while Col. Paul Foster barely manages to escape through an airlock. Once the sphere is repaired and William's remains cast into space, Paul deploys a team to investigate what happened. Commander Straker wants the alien captured alive for study.

Paul travels to earth to visit Tina, his girlfriend, before Straker brings him back to moonbase aboard a shuttle. Reconnaissance craft have by now revealed the UFO's position and Straker sends two moon-mobiles to investigate. Led by Paul, the mobile team disembark and approach the seemingly abandoned UFO, which unexpectedly opens fire.

As SHADO Interceptors close in to destroy the hostile alien vessel, Paul tries to reach a moon-mobile but falls and damages his radio. The interceptors arrive and destroy the fleeing UFO, which crashes into one of the moon-mobiles and explodes. The rest of Paul's team escape in the surviving vehicle and return to base, believing Paul to have been killed in the blast.

With his oxygen supply rapidly depleting, Paul begins to make his way back to the moonbase on foot, but is apprehended by the UFO's alien pilot, who has also survived the blast. Paul is frogmarched until he manages to grab the alien's rifle. But the alien threatens to destroy the remaining oxygen canister and Foster is forced to relent.

Meanwhile, having told his second-in-command, Col. Alec Freeman, to inform Tina of her boyfriend's apparent death, Straker offers Paul's vacant command to Lt. Mark Bradley. Bradley, a black man, accepts - but reluctantly, since he believes racism among the crew may become an issue.

Unable to communicate verbally, Paul and the alien help each other across the treacherous moonscape. When Paul almost suffocates, the alien revives him with a fresh supply of oxygen. The pair later traverse a chasm by means of a rope bridge and the alien saves Paul's life a second time when the rope suddenly gives way.

Both are almost dead from lack of oxygen when Paul spots a SHADO rescue vessel. But Paul's rescuers misunderstand his muted pleas to hold fire and the men shoot the alien dead. Paul returns to Tina, who can no longer cope with the stresses involved in her boyfriend's job. The couple agree to separate.