[2] It is 515 days after leaving Earth orbit, and Helena Russell and Maya are preparing for a formal party to be held the next evening.
Helena suggests to Maya a different hairstyle might be more appealing to would-be suitor Tony Verdeschi; the Psychon woman uses her power of molecular transformation to instantly produce a new coiffure.
By the time the senior staff has gathered in Command Centre, what started as a minor malfunction in the main electronics has grown into a cascading systems failure.
She tells them Moonbase Alpha is being held in an electro force-field, which is not only suppressing their power but can immobilise their voluntary nervous systems.
Permitting them forty-eight hours of minimal life-support, Zamara haughtily announces two Alphans are required to return with her to Vega for an undisclosed purpose.
As Helena wanders amid the foliage, she is startled by a being with an immobile plastic face wearing a hooded grey coverall with the numeral '8' on the chest.
The Alphans are joined by other Vegans, all of them perfect physical specimens; the men bare-chested and virile, the women shapely and lithe.
An attempt to procure power-packs from the Eagles fails; with the travel-tube network non-operational, the launch pads are inaccessible.
When his people were overwhelmed by a sudden and severe climatic change, they built service robots and linked them with a complex computer.
While investigating the computer chamber, Verdeschi and Helena discover it is protected by a powerful energy barrier impervious to laser fire.
Worse, calculations show the Moon is now two light-years distant from its previous position in the Vega system; they must have travelled through a time warp during the positronic transfer and arrived weeks in the future.
Her last experiment a failure, she is reviewing the entire micro-disc library for a literary example of humans driven to commit murder.
Her search ends with Shakespeare's Othello, discovering the emotion of jealousy can compel humans to kill.
Watching the tender reunion between Koenig and Helena, Zarl is uncertain and questions if they could be missing something by rejecting the emotion of love.
Zarl's advances are blatant, but Helena's response is impassive; she is concerned that any resistance could be translated into an act of aggression.
Maya returns with grave news: the computer has a fail-safe mechanism—interference with its power source initiates an explosion that could destroy the entire planet.
Goaded on by Zamara, Zarl practices death-blows with his powerful android fists, smashing furniture and statuary.
Ignoring Zamara's shrill protests, Zarl takes Helena's outstretched hand and presses it to his lips.
'Storm at Sun-Up' by Canadian jazz composer Gino Vannelli, was selected by choreographer Lionel Blair to accompany the seduction dance during filming, and served as Wadsworth's inspiration when preparing his score.
[3] A brief moment of the 'space horror music' composed by Vic Elms and Alan Willis for "Ring Around the Moon" can be heard when Zarl takes Helena's hand and says, 'The play begins.'
The viewer would have seen a restored Alpha dispatching a recovery Eagle, and Alan Carter arriving on Vega with cold-weather gear for Koenig and company.
With the Vegan city powered down, the Alphans discuss the future with the Numbers, who are looking forward to re-learning the basics of survival in their world's harsh environment.
Feeling the new American producer Fred Freiberger did not appreciate her contribution to the previous series and not seeing any potential change in the foreseeable future, she opted to depart.
[5] Merton would change her mind and return to the show three months later, but during her absence, her character would be replaced by Japanese operative Yasko.
Coming off her critically acclaimed, award-winning performance as Mrs. Baylock in the 1976 horror film The Omen, Billie Whitelaw was cast as the sensuously diabolical android Zamara.
A veteran of British theatre, her stage-trained voice had to be modulated in post-production to prevent it from overwhelming all other elements of the soundtrack.
The red nylon quilted jackets introduced in "Dragon's Domain" were worn here by Catherine Schell and background extra Robert Reeves.
[3] Apart from simple laser-beam overlays, teleportation energy-flares and one big-screen shot with a burn-in of the star-chart showing the before-and-after positions of the Moon, there are no substantial visual effects in this episode.