"The Mark of Archanon" is the eighth episode of the second series of Space: 1999 (and the thirty-second episode overall of the programme). The screenplay was written by Lew Schwarz; the director was Charles Crichton. The final shooting script is dated 12 April 1976, with amendments dated 21 April, 26 April, 27 April and 28 April 1976. Live action filming took place Tuesday 4 May 1976 through Tuesday 18 May 1976.
Story
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). The two mates banter as they set up a sonarscope and begin probing the cavern walls for the mineral. Johnson soon detects a mineral formation that is definitely not dylenide. Using the 'scope's thermal cutter, they uncover a transparent cabinet—containing two persons.
The occupants are humanoid—a man and an adolescent boy—standing immobile and apparently lifeless. Carter, thinking he sees movement within the cabinet, tries to brush away dust for a better look. Before his hand touches the glass, he is thrown back by a powerful force-field. 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.
Rescue and medical teams arrive. Carter recovers from the shock while the others continue excavating the alien chamber. Despite the astronaut's insistence he saw the man's eyes open, scans of the aliens show no sign of life. With an internal temperature of 4 °C, the cabinet is definitely not a cryogenic suspension unit. 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. The aliens are being held in a state of suspended animation. A second artefact is uncovered next to the cabinet: a control panel and power source. However, the excavations have weakened the cavern roof. With the ceiling collapsing, Verdeschi blindly manipulates the control panel and manages to deactivate the force-field. The adult alien is pulled to safety as the now-unprotected cabinet is smashed by falling debris. Carter risks his life by re-entering the cave-in to bring out the boy.
Though still unconscious, the aliens' vital signs quickly normalise. Helena and her assistant doctor, Raul Nuñez, tend to the youth. Unobserved, the man wakes and reaches for a discarded pick-axe. As he regards the Alphans with increasing hostility, a representation of the 'Flammon' danger symbol glows into existence beneath the skin of his forehead. When he hears the boy is safe, both his anger and the symbol fade before he again loses consciousness. The two are taken to the Medical Centre, where tests conclude their physiology to be borderline human.
When left alone in a supposedly sedated sleep, the man, known as Pasc, rises. He awakens the boy, his son Etrec. The youth is terrified his forehead also bears the symbol and asks his father to kill him so it cannot come. 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. Instead, he wraps his head with a bandage to hide the damning mark from sight.
From Command Centre, Verdeschi and Helena transmit news of the discovery to John Koenig on Eagle One. The Commander is leading a long-range survey mission in an area of space designated 'Blue Quadrant'. At present, his ship is traversing a dense asteroid storm and contact is marginal. As for the aliens, Koenig insists all security procedures be strictly observed. The discussion is interrupted by the sudden entrance of Pasc and Etrec. 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.