[4] It is 640 days after leaving Earth orbit, and Alan Carter sings an absurd ditty as he strides through an underground mining gallery beneath Moonbase Alpha.
Mineralogist Andy Johnson leads the way, searching for dylenide crystals (a component in the Eagles' atmosphere-scrubbing filters).
As Johnson kneels to check on Carter, he glances at the aliens—and is shocked to see the adult's eyes are open, glaring at him with a burning intensity.
Tony Verdeschi spies a familiar symbol etched in the glass, recognizing it from a past planetfall on Krom Two.
Known as Flammon the 'Death Glow', Helena Russell states the symbol was left by a visiting god-like race to warn the indigenous population of areas containing life-threatening danger.
(This 'Krom Two/Flammon' dialog between Tony and Helena is purely plot exposition, not a reference to any past filmed episode as there isn't one containing these elements.)
When focused on the adult for a longer span of time, the equipment records a greatly protracted heartbeat and a minuscule increase in the volume of air in the lungs—he is alive.
As he regards the Alphans with increasing hostility, a representation of the 'Flammon' danger symbol glows into existence beneath the skin of his forehead.
Pasc, face contorted with a psychotic rage, the symbol pulsing on his forehead, reaches for Etrec's neck—but cannot bring himself to strangle his son.
From Command Centre, Verdeschi and Helena transmit news of the discovery to John Koenig on Eagle One.
Pasc deflects Helena's questions about the bandage and his 'wound' by telling her a man's blood holds spiritual significance on Archanon and cannot be viewed by strangers.
Pasc informs them his people long ago outlawed violence, replacing evil with good.
Led by Pasc's wife Lyra, the madmen imprisoned father and son in the stasis chamber.
After initially refusing, Etrec leaps on him piggy-back style as he sees Pasc approaching the astronaut from behind, a pair of surgical scissors raised to stab him in the back.
Pasc's startled reaction goes unnoticed as Helena calls the techlab, asking for the Archanons to report to Medical.
Perhaps not coincidentally, recordings of Pasc's brain waves show a series of distortions not present in the boy's.
Security men are dispatched to locate the lost aliens, who are found as they board a travel tube servicing the launch pads.
When asked what became of the Archanons' abhorrence to violence, Etrec reveals his father has the dreaded 'killing sickness', as denoted by the mark on his forehead.
Helena attempts to learn more about the killing sickness, which she equates with the active virus discovered in his system.
Verdeschi sends a reluctant Carter to convince the boy to first give blood, then consent to leave with his father if necessary.
Forehead pulsing with the hated symbol, the boy turns on his friend, a steak-knife poised to strike.
A stasis chamber was prepared and, knowing susceptibility to the disease is carried in the genes of the male line, both husband and son were imprisoned until a cure was found.
Physiologically unable to produce blood rapidly, no Archanon could give the amount required to prepare the serum and survive.
With Sir Lew Grade's late renewal order for the second series, a strict ten-month production schedule was imposed by ITC New York.
The scripts would be written to heavily feature one of the stars; the other would appear in a reduced capacity while working on their own, concurrent story.
('The Rules of Luton' was filmed simultaneously on location, with Landau and Schell receiving the majority of the screen time.)
"The Mark of Archanon" shooting script dated 12 April 1976 contained scenes either cut for time or revised by the subsequent amendments: (1) The use of dylenide crystals in the Eagles' air filters was mentioned in dialogue between Carter and Johnson during the hook.
(2) The cave-in would be an accident caused by a careless technician; when not in use, the thermal cutter was left turned on and pointing at the ceiling; (3) Carter's use of the nickname 'Bluey' for Johnson was explained as Australian slang for people with red hair; (4) The plan to gain access to Pasc's Eagle by burning through the propulsion-tube's inspection hatch with acid was visualised and carried out by two Alphans.
This sequence was removed for budgetary reasons; (5) The new character of Raul Nuñez was created when a scheduling conflict would prevent actor Jeffery Kissoon from portraying Ben Vincent, as intended by the script.
The story would be adapted from the 12 April 1976 shooting script and contained many of the unrevised and deleted items present in this draft.