Moonbase Alpha Wiki

Episode Quote[]

"To attempt to preserve your personality is the ultimate vanity."

Plot Summary[]


A strange craft approaches Alpha, and Computer is unable or unwilling to provide any relevent data. It sends a transmission consisting of audio only, asks for help, and permission to land. It comes into visual range and appears on the main screen.

Koenig agrees to let it land, on the stipulation that it does so away from the base. It continues to approach until Koenig says that is close enough. The Alphans offer to receive a small, un-armed delegation from the craft. An offer which is refused, but an invitation is extended to John, Helena and Victor to come aboard, "fully armed of course".

Act One[]

They hesitantly agree, and take a moonbuggy out to the ship. They are guided to the control room by the voice. When they arrive they enter a massive, seemingly empty room. They look for the source of the voice and find an elderly man sleeping in an adjoining chamber. He awakens and seems confused by their presence.

They ask what kind of help he needed and he seems to have no idea to what they refer. He introduces himself as "Companion", and tells them that he and Gwent occasionally have to interrupt their endless journey to aquire items necessary to their well-being, and surmises that is the reason for their being summoned. A list of provisions seems to print out on it's own, and Companion begins to chastise his absent friend for interrupting.

Victor looks at the list and says that they might have some of the items. The voice of Gwent replies that he has consulted their computer and they have everything on the list. Koenig is allowed to contact the base to verify this, but Companion tells him that Gwent is the ship around them, and controls their computer, and which will tell them whatever he wants. He suggests they give him what he wants and leave... while they still can. It becomes apparent that Companion is dying. Koenig agrees to send the supplies when they return to Alpha. Gwent demands he get the supplies first.

Koenig orders an attack, and Gwent retaliates. Companion collapses as they reach a truce. He tells them that Gwent has never lived alone. With his dying breath, he confesses that he is Gwent, but the machine outgrew him and became his master. He dies and Gwent lifts off.

Act Two[]

A service is held for Companion and his coffin is launched into space. Gwent demands the supplies be delivered, and warns that there is no one to restrain him now. Gwent "goes away" and leaves his captives alone in the dark.

Act Three[]

Victor stumbles into a forcefield that drains his artificial heart of energy. Gwent returns at that moment, but cannot see what is happening. He has John and Helena seperate so he can see. He revives Victor with a bolt of energy.

It has become apparent to Koenig that Gwent can see only with the use of a spotlight-like probe. He informs Helena and Victor in writing. In order to use the element of surprise, he contacts Main Mission, says nothing, but writes out "attack!". Alpha launches Eagles and dispatches laser tanks to try to incapcitate Gwent. They fire upon Gwent to no avail. And Gwent's counter attack is devastating.

As Koenig watches the death and destruction he suspects that he and his people are outmatched by their opponent. He is is ultimately convinced when Gwent fires a beam that causes incredible pain to the entire base. Koenig surrenders and orders the supplies delivered. Gwent tells his captives that he will release Victor when they arrive, but John and Helena will remain as his companions.

Act Four[]

The Eagle docks and the supplies are unloaded. Gwent detects the Alphans weapons and decides to keep Victor as punishment for their treachery. Koenig orders them to fire on the door separating them. This has no effect and Alan and the security team are forced to leave. Gwent instructs John and Victor to get the power core from the supplies and install it. Koenig decides to destroy the core and Gwent by depriving him of energy.

Gwent is taken aback by their actions. He becomes regretful of his actions and realizes the inherent flaw of transferring his personality into an all-powerful machine. He needs companionship. He sees that his vanity was his greatest sin and welcomes the release of death. His systems shut down and John Helena and Victor are trapped within the dead machine.


As the air thins, Koenig places a small piece of the smashed fuel core into the chamber and the lights start to come up. John tells him they need oxygen, not lights, and oxygen starts to fill the room. Gwent opens the door and lets them out. Koenig stops to say goodbye to Gwent on the way out, feeling pity for this lost, lonely creature. When they get back to the base, Gwent lifts off. He is heading directly for the base, and not gaining altitude. The Alphans watch as he barely clears the base and flies into a mountain, and is destroyed... a blind, lonely creature looking for his death.


International Titles[]

  • France/Canada - La machine infernale/The Infernal Machine

Spain - La máquina infernal/The Infernal Machine Germany - Die Teufelmaschine/The Infernal Machine Italy - La macchina infernale/The Infernal Machine Japan - Space Devil/Infernal Machine Portugal - A Máquina Infernal/The Infernal Machine Sweden - Maskin eller Människa/Machine or Man South Africa - Die Gevaarlike Masjien/The Dangerous Machine

Final draft script 11th December 1974

Filmed Friday, December 20th - Tuesday, December 24th, 1974, Monday, December 30th - Tuesday, December 31st, 1974, Thursday, January 2nd - Thursday, January 9th, 1975


  • Int. Main Mission
  • Int. Koenig's Quarters
  • Int. Alpha Corridor
  • Int. Eagle Pilot Section
  • Int. Gwent Antechamber
  • Int. Gwent Main Chamber


Gwent was built in two scales (plus larger sections for the lift and Eagle docking). The big model was smashed by Nick Allder immediately after filming, in frustration after problems making the ship roll correctly.

Three laser tanks were also built, to scale with the 44" Eagle. They were seen briefly in the This Episode clips of The Last Enemy and one appears in the Eagle hangar in Space Warp.

The 3 tanks and 2 Gwents were built by Martin Bower in 12 days.

Stock footage of a manoeuvring Eagle is from The Last Sunset (also seen in War Games).

Stock footage of an Eagle being shot over the Moonbase is from War Games.


Library tracks: "Mission Control" composed by Harry Soskin (Chappell Recorded Music Library)

"Outer Space" composed by Robert Farnon (Chappell Recorded Music Library)

"Lunar Landscape" composed by Roger Roger (Chappell Recorded Music Library)

"The Monsters" composed by Ivo Vyhnalek (Chappell Recorded Music Library)

"Dark Suspense No. 1" composed by Beda Folten (Chappell Recorded Music Library)

"Subterranean" composed by Joe Venuto (Chappell Recorded Music Library)

"Celestial Mirror" composed by John Cavacas (Chappell Recorded Music Library) was listed on cue sheets but not used.


There is no obvious reason why Gwent violates aerospace rules (the shape is symmetrical with rockets behind). The idea that bumble bees cannot fly was based on calculations from fixed wing dimensions; as the bees swivel their wings during flight, they generate more lift.

How do sensors detect a body (and that it is dead)? Infra-red (thermal imaging is sometimes used to detect bodies, and survivors, in smoke and debris)?


Alpha Personnel: Unknown number of fatalities: perhaps 2 laser tank crews, 3 Eagle pilots.

Alpha Technology: Bergman's artificial heart is used again (it was introduced in Black Sun and used in Guardian of Piri and Force of Life).

The laser rifle is seen. It is also used in War Games, Dragon's Domain and The Metamorph and is often seen in other episodes.

We see the laser tanks for the only time. There are three designs, and perhaps six in total (two are destroyed). They are also glimpsed in the THIS EPISODE titles of The Last Enemy

Eagles: Eagle 1 and 2 (armed); 4 (supply) (2 Eagles are destroyed).

Planets: None.

Aliens: Delmer Powys Plebus Gwent from planet Zemo. Humanoid.

Props: Companion's bed was used as Arra's throne in Collision Course and as the Archon's throne in The Dorcons


Many high and distant shots emphasise the size of the sets, and the loneliness of the central character. Mirrors and paintings of receding corridors further increase the perceived size of the sets. An award-winning chair by Finnish designer Eero Aarnio, the Pastilli (1968), is used as set decoration: two are chairs, others are placed on top of two stacked Ditzel barstools to form columns. Both also appear (in black instead of red) in Mission Of the Darians.

Gwent and Powys are counties in Wales created in 1974. Gwent means "The Place", Powys is an ancient kingdom whose name means "province".

The title is from Jean Cocteau's 1934 play "The Infernal Machine" showing Oedipus crushed by a hostile world. "One of the most perfect machines constructed by the infernal gods for the mathematical annihilation of a mortal".

"Said the spider to the fly". Bergman is quoting The Spider and the Fly, a poem by Mary Howitt, published in 1829. "Children's stories are brutal, Professor, but you have nothing to fear." "Except fear itself." Bergman's reference here is to Franklin D. Roosevelt in his first inaugural address in 1933 ("the only thing we have to fear is fear itself", referring to economic pessimism in the Depression).

During a make-up session, Prentis Hancock was discovered to have a small tumour on his neck. During the filming of this episode he was in hospital having it removed. He was replaced for this episode by Gary Waldhorn (Winters). Morrow is said to be recovering from fractured ribs and a broken ankle. .

In the This Episode sequence, one shot shows the Moonbase through the rotating paddles of Gwent.

Having completed his stint on Barry Lyndon (1975), director David Tomblin returned to the series with this episode.


Season 1
Breakaway I Earthbound I Black Sun I Missing Link I Voyager's Return I Matter of Life and Death I Ring Around the Moon I The Last Sunset I Alpha Child I Death's Other Dominion I Force of Life I Guardian of Piri I The Troubled Spirit I The Last Enemy I Collision Course I Dragon's Domain I The Full Circle I Mission of the Darians I End of Eternity I War Games I The Infernal Machine I Another Time, Another Place I Space Brain I The Testament of Arkadia
Episodes are listed in the order suggested by Andrew Kearley.