Director Caulder (Donald Houston) is being pressured by the counsel for Moonbase 3 to cut costs. Especially in light of all the problems they have been having. The counsel is sending Franz Houser (Victor Beaumont) for an accounting of what is going on at the Moonbase and an update on the projects the scientists are working on. There are a couple projects that are being researched and tested that have potential in the advancement of science as well as being marketable. If Caulder can give Houser positive results, it will justify the expense of keeping Moonbase 3 open. Stephen Partness (Tom Kempinski) and Peter Conway (John Hallam) are both working on separate projects that have the potential of doing just that.
Partness is working on a new fuel based on a new element that would be more efficient and cheaper to make. Partness is not well liked by the people at the base, except for Conway. He was previously in trouble for creating some explosives that resulted in the death of Professor Laubenthal (Peter Miles). Caulder is all for sending him back to Earth, but Partness assures him that he is close to a breakthrough, so he allows him more time.
Conway is working on a metal foaming process that makes metal lighter and stronger thus perfect for space applications. The research and experiments must be made on the Moon where the gravity is lighter. Foaming metal on Earth would be impossible, at this time. Conway is trying to complete and perfect the process so it can be studied, and applications created that would allow the manufacture of the foam metal in Earth’s gravity.
When both Partness and Conway tell Caulder that they have each achieved breakthroughs in their projects he is elated. Finally, he has something to show for all the hard work the researchers of Moonbase 3 have put in. He is also hoping for more appropriations to keep the research facility going. Things, however, are not as perfect as the two scientists let on. Stress from the pressure of producing results has resulted in the falsifying of results and has pushed both men to the point of having psychological breakdowns.
The spacesuits used on Moonbase 3 were also used in the Doctor Who stories "Invasion of the Dinosaurs" 1974 and "The Sontaran Experiment" 1975. Some of the dialog used during the rocket launch scenes for the series was taken directly from NASA Apollo mission transcripts.