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Revision as of 17:05, 16 July 2020

The AB Chrysalis
Episode B-11/12/12/12
Production Info
Director Val Guest
Story by
Screenplay by Tony Barwick
Production Code
IMDB Ref tt0706311
Previous New Adam New Eve
Next Catacombs of the Moon
Transmission Info
Season 2
Episode 12
Airdate 18 November 1976
Previous Episode Seed of Destruction
Next Episode Catacombs of the Moon
Chronology[N 1]
Story date(s) (Alpha Date): Mon 24 Mar 2003[N 2]
Previous Catacombs of the Moon
Next The Beta Cloud


"Forget logic. Recognise desperation."


A planet on which people enter a chrysalis stage when they reach their allotted span.... Reborn, they attain new heights of mental and physical perfection...but for Moonbase Alpha, the planet threatens disaster.



The moon is moving into a region of space where explosions, causing massive shock waves, occur at 12 hour intervals. As Alpha moves closer, it begins to suffer more damage and sustain more casulaties. To avoid unnecessary loss of life, the bulk of Alpha's population is evacuated to a holding position on the far side of the moon, to shield them from the force of the shock wave. The command staff along with some medical and technical crew remain on Alpha to keep the base operational and monitor incoming data. The shock wave hits, causing damage to vital systems.

Act One:

With 12 hours before the next one, Koenig leads a mission to the planet at the heart of the shock wave, to see what is causing the blasts, and if they can be stopped before Alpha is destroyed. Detecting high energy levels on the moons that surround the planet, they decide to investigate the closest one. Homing in on the energy source, they find a small installation consisting of five metallic structures. They land in their midst, and Koenig goes out to look around. He enters one of domes and is taken undeground by an elevator. He exits into a room filled with black and white globes on pedestals of varying heights. He is struck by an bolt of energy and knocked unconscious. Maya alerts Alan, who goes in after him. Alan finds Koenig lying unconscious on the floor, but is able to rouse him. One of the globes begins to move from pedestal to pedestal, ending up by a communications device, where it attempts to communicate with them. It begins with a series of geometric shapes, then moves on to star charts. Koenig draws a representation of our solar system and points to the third planet. The probe recognizes it as Earth and provides a suitable atmosphere. Koenig asks to speak to someone of authority to see if he can get them to stop the shockwaves. The probe responds that that is not possible, as it's masters have yet to be born.

Act Two:

It then suggests that they leave the dome, stating that they are in danger. Maya contacts them to tell them that the energy is building to a critical level. They return to the Eagle, but before they can lift off it is struck by a wayward energy bolt. They manage to get the circuits back online and lift off before their ship can be damaged any more. Koenig decides to visit the planet below. They land, and without warning, the Eagle is lowered beneath the planet's surface. The voice of another probe, tells them that they are being taken to a place of safety. When the Eagle comes to rest in a subterranean cavern, the probe tells them that a suitable atmosphere has been arranged. They leave the ship, and the probe greets them. They find out that it's masters have a unique life cycle in which they grow old, but instead of dying, enter a chrysalis and are reborn. They learn that one of it's masters has not entered the chrysalis and ask to speak to him. The probe sets up a chamber for them to talk to the guardian. The probe translates Koenig's plea to stop the next shock wave but it's too late. The guardian has gone senile and must enter his rejuvination chamber. Alan panics and tries to stop the guardian from being taken out of the room and breaks the seal on the casket. The probe has to seal the room so that the guardian can have the chlorine gas environment that he needs to survive. Alan gets trapped and starts to suffocate.

Act Three:

Maya transforms into a creature capable of breathing chlorine gas and the probe lets her enter. She pulls Alan out with Koenig's help, and they return him to the Eagle. Koenig decides to force the probe into stopping the blast by telling it that he will give the order to destroy it's master's rejuvination chamber, with the laser on the Eagle, if it does not comply. It stuns him to prevent him giving the order. Alan wakes to find Maya uncertain as to how she should proceed. Alan suggests firing the laser, but Koenig wakes in time to stop her. He offers his ultimatum again, and is stunned again. Alan tells Maya to fire, but is stopped by the voice of one of the first aliens to be reborn. Koenig orders the laser disarmed, and is lead, by the probe, to meet with it's masters. With no human equivalent for their names, they introduce themselves as 'A' and 'B'. Koenig makes his plea again. 'A', who finds him attractive, votes in his favor. 'B', who finds 'A' 's reasons foolish, votes against. With a tie, they must await the birth of another, deciding vote. 'B' informs Koenig that the next to born will be the brother of the guardian, that Alan almost killed. She doubts that he will be inclined to vote in their favor.

Act Four:

When he emerges from his chrysalis, he does deny Koenig's request to stop the blast, but offers to let them stay with them, where it is safe. Even with the knowledge that Alpha has now moved out range, Koenig declines. He tells them that there are things more important than safety, "loyalty is better than logic. Hope is better than dispair... and creation is better than destruction." He leaves the chamber to find Maya and Alan ready to face an uncertain future at his side. 'A', 'B', and 'C' discuss Koenig's motivations. 'B' and 'C' are baffled but 'A' seems to grasp them. Alan manages to fly the Eagle up the narrow elevator shaft that leads to the surface. They head towards Alpha with no real hope of either reaching it, or surviving the impending shock wave. John contacts Alpha. He tells Helena that they will not be able to make it back. He asks to be patched into the interbase system, and warns the base of the gravity of their situation. He commends them for their devotion to duty since they left Earth orbit. The shock wave comes, but to their surprise, it does not destroy their Eagle, but increases it's speed enough to reach Alpha, which the shockwave passes over with minimal effect.


When they get back, Helena asks John about the alien women. She had heard from Alan that they were "beautiful, naked and green". John starts to tell her that he could barely see them, but when pressed, tells Helena that he hadn't noticed that they were green.[1]



Original Title: The Chrysalis A B C

International Titles:

Country Title (Translation)
Belgium (Flemish) Spiegelbeeld)
Denmark Pupperne (Chrysalis)
Spain Las crisálidas A y B (The chrysalis A and B)
France/Canada Les chrysalides AB (The Chrysalis AB)
Germany Planet der Wastenden (Planet Of Waiting)
Italy Le crisalidi (The Chrysalids)
Japan Space Lightning! Shockwave)
Portugal As Crisálidas A-B (The Chrysalids A-B)
Portugal Planeta das Crisálidas (Planet of the Chrysalids)

Shooting script titled The Chrysalis A B C dated 18th May 1976. Yellow page revisions June 30th (during filming, from 18th June-6th July).

A "Double Up Koenig" script, filmed simultaneously with Catacombs Of The Moon


  • Int. Command Centre
  • Int. Medical Centre
  • Int. Power Room
  • Int. Weapons Section (screens only)
  • Int. Alpha Corridor
  • Int. Travel Tube
  • Int. Eagle Pilot Section
  • Int. Eagle Passenger Section
  • Int. Alien Elevator
  • Int. Underground Space Station
  • Int. Alien Tunnel
  • Int. Chamber
  • Int. Rejuvination Chamber
  • Int. Conversation Chamber


The spheres were 5ft (1.5m) tall, so big that Martin Bower couldn't get them out of his workshop door; he had to saw through the door frame.

The effect of the final explosion is also used in Space Warp.

The voice probes were fibreglass and blown by compressed air. They were filmed at 4 times normal speed (94 feet a second) and reversed, so the voice probes bounce in slow motion up to the stands. In some shots the stand wobbles before the probe reaches it. There is only one shot of the actors and probes together.

The alien elevator is used on Alpha in Space Warp and The Seance Spectre.

The DVDs contains behind-the-scenes footage taken at Bray Studios during the filming of this episode (especially the Eagle landing on the planet), with a commentary by Brian Johnson.

The spheres were reused as the waste domes in The Bringers of Wonder


Chlorine is a greenish yellow gas, a very powerful oxidising agent that is highly toxic to all life. It is like oxygen in that it burns with very exothermic reactions, so it is possible that another type of life could evolve to breathe it. Naturally it is rarely released (like oxygen), so a chlorine atmosphere must be created by an evolved biosphere (as Earth's atmosphere was). It is unlikely that lifeforms so identical to humans would evolve, so similar as to be attracted to Koenig.

Alan collapses and is unconscious for some time. This probably means permanent lung damage. Chlorine attacks the capillary blood vessels in the lungs, causing the lung tissue to inflate into a wet spongy mass through which gas exchange is not possible (a condition called pulmonary oedema); the victim suffocates to death. It was used this way in gas attacks in World War I.

Although some animals undergo metamorphosis from a larval to an adult form, the aliens use it to rejuvenate and have a long lifespan suggesting it is an artificial hibernation.

From one large circle and four smaller but identically sized circles the voice probe assumes they are from Earth. It also assumes all Earth people speak English.

Explosions at regular 12 hour intervals do not necessarily suggest intelligence- as the Alphans prove by slipping past the defence easily. The explosions actually draw attention to the planet.

Electric charges cannot travel through the vacuum of space. The effects suggest a real explosion with a slower-than-light debris shockwave.

Maya calculates their ETA to 2 decimal points of a second- absurd precision which takes longer to say.

Koenig's blast procedure leaves something to be desired- kneeling by the sharp corner of a desk covering his ears.

From a few circles, the aliens deduce the exact solar system the Alphans are from.


Chronology: 1288 days after leaving Earth orbit (Mon 24 Mar 2003)

Alpha Personnel: 0 fatalities.

Alpha Technology: Eagles: Eagle 1 (Koenig)

The Eagle laser turret is used. It is also seen in The Seance Spectre and Devil's Planet. The laser controls are the same as Osgood's trigger in Catacombs of The Moon. It is different to the one in The Seance Spectre, which was also used to control the Research Station laser in The Exiles.

The forward view screen is seen for the first time. It is also seen in Seed Of Destruction, Space Warp, Bringers Of Wonder part 2, The Seance Spectre and Devil's Planet.

One scene shows eleven Eagles in one shot. Four have booster pods.

Maya transformations: Kreno animal

Planets: Unnamed planet

Aliens: A, B, C, guardian, all humanoids

Props: The screen on the alien moon made from perspex is used as the screen in Space Warp

Footage: Pan over Alphan buildings is reused from The Exiles.

Shot of a corridor explosion and the wreckage inside is reused from The Exiles

Shot of an Eagle landing on a steaming launch pad is reused in Catacombs of the Moon.

Cast: Robert Rietty also dubbed the voice of Luke Ferro in The Testament of Arkadia


See more observations


At the end, Helena questions Koenig about "those women on the planet. Beautiful and naked, I understand." and he claims he didn't really notice. In the script she throws her commlock at him.



  1. Based on order suggested by Andrew Kearley (See Season Navbox for full list)
  2. See Alpha Date/Non Time Warp Date for a more detailed explanation of Second Season Story Dates.


Season 2
The Metamorph I The Exiles I One Moment of Humanity I All That Glisters I The Mark of Archanon I Journey to Where I The Taybor I The Rules of Luton I New Adam New Eve I Brian the Brain I Catacombs of the Moon I The AB Chrysalis I The Beta Cloud I Seed of Destruction I A Matter of Balance I Space Warp I The Bringers of Wonder - Part 1 I The Bringers of Wonder - Part 2 I Dorzak I The Seance Spectre I Devil's Planet I The Lambda Factor I The Immunity Syndrome I The Dorcons
Episodes are listed in the order suggested by Andrew Kearley.