It is 1912 days after leaving Earth orbit, and the routine in Command Centre is suddenly interrupted by a series of whoops and exclamations from the speakers.
As the three domes store the atomic waste from Moonbase Alpha's reactors, Tony Verdeschi is concerned an impact could generate a nuclear explosion.
If the Commander's reckless behaviour continues, a crash is inevitable; Verdeschi orders Carter to take nuclear physicists Jack Bartlett and Joe Ehrlich with him on the rescue pod-equipped Eagle.
Carter lands at the crash site and rescue workers board the burning Eagle, pulling Koenig to safety in the nick of time.
Carter welcomes his best mate, astronaut Ken Burdett, while Sandra Benes rushes into the arms of her fiancé, pilot Peter Rockwell.
Ehrlich trades golf handicaps with his cousin Henry and Bartlett greets his friendly rival, physicist Professor Hunter.
As Diana Morris, an old flame of Koenig's, searches the crowd for the Commander, Carter tries to chat up Louisa, who turns out to be Doctor Ben Vincent's fiancée.
Englishman Bartlett swells with pride when he hears the transluminal drive was developed by researchers at Cambridge—but is disappointed when Hunter the American smugly reveals it was Cambridge, Massachusetts.
A development of the ion rocket, it can make loops in the space-time continuum; travel time back to Earth, subjectively, is a matter of hours.
Guido tells them the Superswift is the advance party; Earth will dispatch proper transport ships to evacuate Moonbase Alpha.
Across the room, Vincent is showing Louisa one of the remote medical relays which allow them to monitor patients from anywhere on the base.
He observes Koenig's obvious distress, but Louisa stares into his eyes and he, in a trance-like state, switches off the monitor.
Guido stands outside a glass partition, watching records clerk Clive Kander; the man's mind is resisting him and he requires help.
Kander is reviewing recordings of recent events, and when he plays the video of the Earth party's arrival, he reacts with horror, then slips under the mental control of the 'Earth men'.
Mesmerised, Kander locks and jams the door, turns the emergency oxygen supply full on, and wrecks the video player.
Kander recoils and smashes into the commlock panel, shorting it out; the sparks ignite the oxygen and the room is engulfed in flame.
A three-man pilot ship, which is also equipped with the light-speed drive that will fly back to Earth and they ask Verdeschi to select an Alphan crew.
Verdeschi and Maya take a recording of the pilot ship's broadcasts to convince Koenig of the true situation, but are ambushed by Sandstrom, who had been freed earlier by Professor Hunter.
As he approaches, Koenig awakens and, as before, sees the alien in its true form, a seven-foot-tall, slime-covered, pulsating heap of protoplasm standing erect on its tentacles.
On the strength of his first script, "New Adam, New Eve", Gerry Anderson and Fred Freiberger commissioned a second submission from writer Terence Feely.
In his version, he had hidden their true appearance until the final scenes of part one, when the 'Doctor Shaw' jelly being moves in to kill Koenig.
[2] A character moment for Helena was cut for time in which she reminisces with Doctor Shaw how the first patient she lost was her father, who had died of a massive heart attack in their home while she was still in medical school.
[6] Attentive viewers will recognise actor Stuart Damon from his previous appearance in the first-series episode "Matter of Life and Death", where he played Parks, the unfortunate survey-mission pilot.
Costumes, props and sets re-used in this episode include: (1) The blue lizard animal Maya transforms into when angered by Diana Morris was a re-painted version of the Kreno animal, previously seen in "The AB Chrysalis" and "The Beta Cloud"; (2) The Ellendorf quadragraphic brain-complex prop was a re-vamped version of the Dorfman artificial-heart test machine from "Catacombs of the Moon"; (3) The nuclear-waste domes were cannibalised from the spherical towers seen in "The AB Chrysalis"; (4) The interior of the pilot ship was originally seen in the earlier Gerry and Sylvia Anderson production UFO as various ShadAir transport planes.
The author would make the jelly aliens the psychically-synthesised minions of a massive non-corporeal space amoeba (which was also the unseen antagonist in the previous segment "The Lambda Factor").