The Ark in Space ( TV story ) The Ark in Space was the second story of season 12 of " Doctor Who " . It was the Fourth Doctor ' s first full , post - regenerative story . It proceeded from a mild - cliffhanger at the end of " Robot " , showing what happened after Harry Sullivan climbed into the police box in UNIT ' s laboratory . It importantly established the location of Nerva Beacon , which would be the narrative lynchpin of the season . " Ark " had a somewhat tortuous scripting process , having slipped past two writer s before its scripts were finally accepted . Both Christopher Langley and John Lucarotti tried and failed to write a script about a space station for season 12 . Of the two , Lucarotti came closest . However , because he then lived on a boat anchored in the Mediterranean — and there was a postal strike afflicting Corsica — Lucarotti was essentially incommunicado to script editor Robert Holmes . It was impossible for Holmes to conduct timely consultation with the " Doctor Who " veteran . Lucarotti was paid fully for his work , and Holmes undertook a page one rewrite , retaining only the central conceit of Lucarotti ' s tale . ( INFO : " The Ark in Space " ) Despite its difficult birth , the story won kudos from the BBC Wales production staff . Russell T Davies once called " Ark " his favourite storyline of the 1963 version of " Doctor Who " , ( DOC : " Inside the World of Doctor Who " ) and Steven Moffat considered it the best Fourth Doctor story , ( REF : " DWM 457 " ) while Barnaby Edwards confessed to being " petrified of the Wirrn " as a child . ( CON : " Do You Remember the First Time ? " ) Tom Baker himself has also stated that , of all the stories he ' d filmed , " The Ark in Space " was his favourite . It was a particularly popular serial with contemporary audiences , as well . Part 2 , in fact , was the fifth - most - watched programme of its week , making it the highest - charting episode of the original version of the programme . In fact , it retained its crown until the transmission of " Voyage of the Damned " , which was the second - most - watched programme of its week . From a production standpoint , it was the first story produced by Philip Hinchcliffe , the new producer after Barry Letts departed from the show . He established a new , darker and ostensibly " Gothic " style of storytelling during his time as the producer of " Doctor Who " . Synopsis . The TARDIS lands on a space station orbiting Earth in the distant future . It ' s seemingly deserted , but the Doctor , Sarah and Harry soon discover that they are not alone . Thousands of human s are in cryogenic sleep , and while they ' ve slept their Ark has been invaded . A parasitic insect race , the Wirrn , have taken control and threaten the very future of mankind . Plot . Part one . An unseen presence approaches a space station orbiting Earth and silently infiltrates it . It reaches a human apparently asleep and unaware . . . The TARDIS materialises in a dark and stuffy room aboard an apparently unmanned station , due to Harry ' s inadvertent interference with the helmic regulator . Once the Doctor turns the lights on , the TARDIS crew decides to look round . Harry presses another switch , unknowingly trapping Sarah in a small control room where the oxygen is rapidly being consumed . By the time the Doctor and Harry find her , she is severely cyanosed . They then find themselves trapped with her . The Doctor repairs the oxygen servos just in time to save them all . He notices that the control cables had been bitten clean through . As Sarah recovers on a nearby couch , the Doctor and Harry are attacked by an automatic sentry system which fires electronic bolts at any moving organic object , including people , a cricket ball and the Doctor ' s scarf . Meanwhile , Sarah is transported from the couch into a chamber where she hears two voices preparing her for a " journey " . The Doctor and Harry deactivate the auto guard by distracting it with Harry ' s shoes and discover that Sarah has vanished . Exploring further into the station , they encounter a slime trail in the corridor but continue into a restricted section holding hundreds of cryogenically suspended humans , along with animal and botanical specimens and an information store . Harry opens a berth and finds Sarah in suspension . He begins looking for a resuscitation unit to revive her and opens a cupboard — only to encounter a giant insect which looms at him . . . Part two . The insect falls to the floor , obviously dead for a long time . The Doctor finds a medical kit but is unsure what to do with it . One of the sleeping pallets activates , and the occupant takes the medkit and sleepily uses it to revive herself fully . She introduces herself as Vira , First Med - tech , and demands to know what the TARDIS crew are doing aboard . She agrees to revive Sarah when she realises her suspension was an accident . Vira explains that solar flare s were threatening to destroy Earth ' s ecosystem and that the government put a select group of humans in suspension on Nerva Station , so they could repopulate the Earth after five thousand years . She is astonished when the Doctor informs her that she has " overslept " by several thousand years because of the alien ' s sabotage . While she tries to revive the station commander , Lazar , or " Noah " as he is known , the power fails again . The Doctor goes down to the station ' s infrastructure to effect repairs and sees a large , green grub in the solar collector , feeding on the solar energy . Noah revives and demands the TARDIS crew removed before they contaminate the genetic pool . He arms himself and proceeds to the control room , where he stuns the Doctor . Vira notices that Dune , the station ' s chief technician , is missing from his pallet . Noah ascribes this to the " regressive " interlopers . He enters the infrastructure to look for any damage the Doctor may have done but is accosted by the grub , which touches his hand and renders him unconscious . Harry and Sarah find and wake the Doctor , only to be escorted back to the cryogenic section by Noah , who keeps his hand firmly tucked out of sight in his pocket . As they return , Vira is reviving Libri , a young technician , who is instantly afraid of Noah . The commander begins to act erratically . He insists the revivals be halted and that Dune is not missing , stating , " I am Dune " , before storming out . The Doctor convinces Libri to go after Noah and stop him . He proceeds to examine Dune ' s cryogenic pallet . He finds membrane from the alien queen ' s egg sac and concludes that the queen laid her eggs in Dune ' s body before she died , and the alien larvae have absorbed Dune ' s knowledge along with his body . Libri , meanwhile , finds Noah in the control room but cannot bring himself to shoot his commanding officer , who kills him before bringing his hand slowly from his pocket . He has started to metamorphose into an alien being . Part three . The voice of the Earth High Minister comes over the station ' s P . A . system to deliver a rousing recorded speech for the awakening colonists , while Noah tries to fight the alien presence in his mind . He contacts Vira and transfers command to her , ordering her to get the sleepers revived and down to Earth as soon as she can . Before he loses control , he says the aliens are called the Wirrn and states , " We shall absorb the humans . " The Doctor and Vira go in search of Noah , leaving Harry and Sarah to revive two more crew members , Rogin and Lycett . Noah , more fully absorbed by the Wirrn , meets the Doctor and Vira in the main corridor and explains that the larvae are approaching adulthood . Vira takes what is happening to Noah very badly ; the commander and she were " pair - bonded " for the colonisation . Harry and the Doctor perform a brief autopsy of the queen and discover the Wirrn are a space - borne species . Vira begins to initiate the next phase of revivals . The Doctor convinces her to delay while he develops a plan to stop the Wirrn . Using the Ark ' s technology , he links his mind to the queen ' s neural cortex , experiencing her last few memories . Meanwhile , a grub breaks into the cryogenic chamber and kills Lycett . Harry and Rogin run to the armoury for fission gun s , narrowly avoiding Noah , and drive the grub back into the air duct with the Doctor ' s help . The Doctor has learned that the queen was killed by the auto guard and decides to electrify the walls of the cryogenic section . He transmat s Rogin and Harry to the control room before the power fails again and realises that the Wirrn must be pupating into adults . He goes down to the infrastructure to turn the power back on , but Noah has almost become an adult Wirrn and advances on the Doctor . The only thing that remains human about him is his face , and even that mutates . Part four . Vira appears at the top of the stairs and fires her stun gun at Noah , allowing the Doctor to get clear . Noah asks Vira to stay and listen to his proposal . If she and the awakened crew - members take the station ' s shuttle , he will order the swarm to let them go . The Wirrn will absorb the remaining sleepers and become a technologically advanced race , like the human pioneers who displaced them , centuries before , from their homeworld in the Andromeda Galaxy . Vira refuses to abandon the Ark , and the crew tries to come up with a way to ensure power will reach the Doctor ' s electric bulkheads . Sarah suggests the shuttle Noah mentioned and volunteers to carry a power cable through the service conduits to the cryogenic section . As she proceeds past the Wirrn , they try to stop her and the shuttle crew from performing their tasks . Two Wirrn are repelled by a test burn from the shuttle ' s engines . Sarah gets stuck in the conduit . The Doctor uses reverse psychology , complaining she is useless in an emergency and not nearly as tough or resourceful as she thinks . Sarah fights her way free , only to realise she has been " conned " by the Doctor . The electricity keeps the Wirrn at bay , but Noah threatens to turn off the oxygen , which the Wirrn don ' t need . The Doctor tries to remind Noah of his human past and urges him to lead the swarm back into space where they belong . Instead , the entire swarm breaks into the shuttle ' s cargo hold and tries to reach the bridge . Vira sets the controls for automatic take - off and disembarks , while Rogin and the Doctor remove the synestic locks that hold the shuttle down . Rogin sacrifices himself by removing the final lock . He is killed by the shuttle ' s exhaust . As the Doctor wonders if Noah led the swarm aboard the shuttle on purpose , Noah radios the station and says goodbye to Vira before sabotaging the shuttle , making it explode in space and proving his humanity had won . Vira vows to get the sleepers revived and down to Earth , but without the shuttle they will have to rely on the transmat . The Doctor , however , notices the transmat receptors on the ground are faulty and volunteers to beam down with Harry and Sarah to fix them , while Vira returns to her duties . Home video and audio releases . DVD releases . Contents : Released : Notes : The additional material is ; A New Frontier : Making The Ark In Space TV Movie Version : Special 70 - minute compilation of the story . Doctor Forever ! - Love & War , Documentary examining the Virgin / BBC novelisation range with Russell T . Davies and Mark Gatiss . Scene Around Six 8mm Location Footage from Tom Baker ' s first story Radio Times Listings , Doctor Who Technical Manual , Crosse and Blackwell and Nestlé promotional material in Adobe PDF format . Digital releases . This story is available : VHS releases . This story was released on VHS in compilation form in Australia and the UK in 1989 in PAL format ( BBCV 4244 ) , though the Australian release was several months prior to that in the UK . The story was re - released in " Complete & Unedited " ( i . e . episodic ) form in 1994 . Audio releases . Excerpts from Dudley Simpson ' s score , arranged by Heathcliff Blair , were released by Silva Screen in the early 1990s on their compilation CD " Pyramids of Mars : Classic Music from the Tom Baker Era " ( FILMCD 134 ) .