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Arc of Infinity was the first serial of season 20 of Doctor Who. Janet Fielding returned as Tegan in this serial, re-joining the Fifth Doctor and Nyssa on their travels. Colin Baker made his Who debut in this story, playing Commander Maxil. Just over a year later, he would take over as the Sixth Doctor at the end of season 21. Of the several Doctor Who stories filmed outside the UK in the late 1970s-early 1980s, this was the only one to open a season.

Arc of Infinity also allowed both Peter Davison and Baker to play antagonists in the story, making them the fourth and fifth actors of the Doctor, albeit with Baker currently playing a different role, to have played both the Doctor and one of the main antagonists in a story, following William Hartnell in The Massacre, Patrick Troughton in The Enemy of the World, and Tom Baker in Meglos.


Omega, an ancient Time Lord made of pure anti-matter, once defeated by the Doctor, is plotting to cross over into this dimension by bonding with the Doctor. Meanwhile, the disappearance of a man in Amsterdam piques the curiosity of his cousin, Tegan, who previously left the Doctor at Heathrow Airport and now finds herself at Omega's mercy. Fearing total destruction from the collision of matter and antimatter, the Time Lords recall the Doctor to Gallifrey to undertake the only viable solution: executing him!


Part one[]

On Gallifrey, a Time Lord is at work, stealing the biodata extract of another Time Lord and killing a technician named Talor who stumbles across the crime. The traitor provides the bio-data to a creature composed of anti-matter and uses the bio-data to invade the TARDIS and then the Fifth Doctor's metabolism. The Doctor's companion, Nyssa, helps him recover. The creature is shielded in this attempt by the Arc of Infinity, a curious curve between the dimensions containing quad magnetism which can shield anti-matter. The Doctor decides to head to Gallifrey to track down the supplier of his bio-data, conscious that, unless the creature trying to cross universes is stopped, its incursion could cause a fatal chain reaction to the universe.

Omega attempting bonding with the Doctor

Omega attempting to bond with the Doctor.

Meanwhile, in Amsterdam, Netherlands, backpackers Robin Stuart and Colin Frazer decide to crash at the crypt of the Frankendael mansion.

During the night, Colin hears something and investigates; he finds a curious birdlike creature, the Ergon, which hypnotises him. A terrified Robin runs away.

The High Council of the Time Lords is also taking the matter seriously and has decreed that the Doctor's TARDIS should be recalled. The Chancellery Guard under the over-zealous Commander Maxil seizes the Doctor and Nyssa. When the Doctor resists arrest, Maxil shoots him...

Part two[]

The Doctor has been stunned to ensure his delivery to the High Council. When he is brought before the High Council, the new Lord President, Borusa, is inscrutable while Chancellor Thalia and Cardinal Zorac are openly hostile; only his old friend Councillor Hedin seems pleased to see the Doctor back on Gallifrey.

The President stresses the gravity of the situation since the creature poses such a threat to the universe, and the High Council has had no alternative but to issue a Warrant of Termination on the Doctor to ensure the creature can no longer bond with him. Fortunately, an old friend, Damon, who is another technician in the records section, provides the Doctor with the proof he needs that a member of the High Council stole his bio-data extract.

Meanwhile, the Doctor's former companion, Tegan Jovanka, arrives in Amsterdam looking for her cousin Colin. Instead, she is greeted by Robin, who tells her that Colin has disappeared. When neither of them can persuade the police to take an interest, they decide to investigate the crypt themselves.

Back on Gallifrey, the Doctor is soon taken for execution, despite Nyssa's attempts to save him, and placed in a dispersal chamber. The sentence is carried out...

Part three[]

The supposed death of the Doctor, however, has not solved the situation. Unbeknownst to the High Council, his mind has been taken into the Time Lord living repository of knowledge, the Matrix, while his body is hidden behind a force shield in the termination cubicle. The creature is a renegade Time Lord, who demands an opportunity to return to the Universe it once inhabited. The truth of the aborted execution is discovered by the wily Castellan, who, while questioning Nyssa and Damon about their involvement, tells them that the Doctor is alive. The Castellan summons and then tells the High Council.

In the crypt, Tegan and Robin are attacked by the Ergon's weapon, a matter converter, and transported into a hidden TARDIS belonging to the renegade. Their minds are scanned, revealing to the creature that Tegan knows the Doctor. The renegade uses Tegan as bait to force the Doctor to obey him, also releasing Colin from his slavery as a reward. The Doctor is returned to normal space on Gallifrey where he makes for the High Council Chamber. Lord President Borusa has fallen under suspicion of being a traitor because the Castellan has revealed it was his codes that were used to transmit the bio-data. The truth, however, is that Hedin is the traitor. He is in awe of his master - the mighty Omega, first of the Time Lords and pioneer of time travel.

Hedin wishes to release Omega from his exile in a universe of anti-matter, not realising the great Time Lord has been driven mad by his years of solitary confinement. The Castellan kills Hedin, but this does not prevent Omega using the Arc of Infinity to seize total control of the Matrix and, therefore, the organisation of Gallifrey...

Part four[]

Fortunately, the Doctor and Nyssa manage to slip away and return to the TARDIS. They use the scant knowledge provided by Tegan to determine that Omega has established his base in Amsterdam on Earth, and head there immediately, desperately trying to find the Frankendael crypt she described. After a lengthy hunt, they find the lair defended by the Ergon, and Nyssa disposes of it with its own matter converter. They reach Omega's TARDIS at the point at which both the ship is destroyed and Omega makes full transference to Earth using the Arc of Infinity. When Omega peels his decayed mask away, he reveals that he now has the same face as the Doctor.

Omega heads off into Amsterdam with the Doctor, Tegan and Nyssa in hot pursuit. Within a short time, the Doctor's prediction of an unstable transfer begins to come true: Omega's flesh decays and it is clear his new body is not permanent. When the Doctor, Tegan and Nyssa catch up with him, it is a painful task for the Doctor to use the Ergon's matter converter on Omega, expelling him back to his own universe of anti-matter. The Time Lord High Council on Gallifrey detects the end of the threat.

Later, once Tegan has checked on her cousin's progress in hospital, she decides to rejoin the TARDIS crew, this time as a willing traveller.


Uncredited cast[]




  • To remain in N-Space, Omega needs to bond with a Time Lord, reversing his polarity. To that end Hedin steals and transmits the Doctor's biodata extract.

The Doctor[]

  • After finding himself "vaporised", the Doctor appears in the Matrix.


  • Tegan has lost her job as an air stewardess and was hoping that meeting Colin Frazer, her favourite cousin, would cheer her up.
  • Damon tells the Doctor that his former companion Leela is well. The Doctor is sorry to have missed her and Andred's wedding.
  • One guard alerts Maxil to the Doctor and Nyssa's presence, while another tries to arrest them.


Friends forever!!

The Ergon next to his creator.



  • The fusion booster is a piece of equipment from Gallifrey, capable of an enormous conversion rate over very short periods and fuelled by anything that contains hydrogen atoms.
  • The Time Lords use impulse lasers.

Time Lords[]

Story notes[]

  • The story had the working titles of The Time of Neman and The Time of Omega.
  • Peter Davison also played Omega in part four when Omega's body becomes a replica of the Doctor's, but was credited on-screen only as "The Doctor".
  • Sean Arnold and Patrick Stewart were considered for the role of the Castellan.
  • Maurice Denham, William Lucas and Glyn Owen were considered for Hedin.
  • Peter Cushing was considered for Borusa.
  • Pierce Brosnan was reportedly considered for Maxil.
  • Lynda Bellingham was considered for Chancellor Thalia.
  • Colin Baker was cast as Maxil after assistant floor manager Lynn Richards recalled seeing Baker in City at the Edge of the World, a 1980 episode of Blake's 7. (TCH 36)
  • Maya Woolfe (Hostel Receptionist) is credited as "First Receptionist" in the combined Radio Times cast for parts three/four.
  • Crowd control in Amsterdam proved to be a major issue throughout the shoot, with Dutch viewers recognising Peter Davison from All Creatures Great and Small. John Nathan-Turner tried to assist Ron Jones in dealing with the onlookers, and indeed is visible in the transmitted version of Arc of Infinity, gesturing away a group of onlookers in the background of the part four scene of the Doctor and Nyssa at the telephone box. At one point, Nathan-Turner's attempts at crowd control became dangerous when an elderly woman assumed he was a thief and attacked him.
  • The Dutch street organ that transfixes Omega for a moment during part four is playing the song "Tulips from Amsterdam". The same music is heard during the establishing shot of Amsterdam at the start of part one.
  • Ian Collier takes on the role of Omega, originally played by Stephen Thorne in TV: The Three Doctors. To keep the return of Omega a surprise, Collier was billed in the end credits as "The Renegade" for parts one and two, with the billing becoming "Omega" for parts three and four.
  • The Radio Times programme listing for part one was accompanied by a black-and-white head-and-shoulders photograph of Lord President Borusa and the Doctor labelled "New Season", with the accompanying caption "Summoned to Gallifrey, planet of all time lords — the Lord President tells the Doctor of his future: 6.45". (original published text)
  • Every story during Season 20 featured a component of a story from the show's past. For this serial, it was Omega, who last faced the first three incarnations of the Doctor in the tenth-anniversary story, The Three Doctors.
  • Tegan is the first companion to have rejoined the Doctor on his travels after having departed, although other companions/recurring characters had previously left the Doctor's company then reappeared.
  • Tegan, while playing a significant part in the serial, has no scenes on Gallifrey, thus does not interact with half of the guest cast.
  • John Nathan-Turner nicknamed Colin Baker "Archie", because he thought he gave "the archest performance he's ever seen in rehearsal".
  • Colin Baker had to remove his elaborate helmet (which he nicknamed Esmerald) as it kept bumping into doorways and arches on the set, so he spent most of the story with the helmet under his arm, against his hip. He later said it felt like he was carrying a chicken around, and took to calling it "the chicken".
  • The story was originally set in London.
  • The original storyline involved the Doctor suffering nightmares about his regeneration, which were actually a precursor to the arrival of an entity called the Avatar, who takes on the Doctor's form and goes to Amsterdam. Operating there as Neman, the Avatar begins to take control of human minds, striving to create a form in which it will be able to permanently maintain its existence. The Doctor and Nyssa discover Neman's plot when they land in a future version of Amsterdam, which is populated by robot guards called Sweepers, the elderly Resisters, and barbaric Anarchs. Realising that history has been altered, they travel back in time to present-day Amsterdam. There, the Doctor discovers that Time Lord regeneration is the mechanism by which the Avatar is made manifest. The Avatar is defeated when the Doctor relives his own recent regeneration.
  • Colin Baker was originally considered for the role of the Castellan.
  • It was Ian Levine who suggested the inclusion of Omega.
  • Cardinal Zorac was originally called Zoral.
  • While visiting Amsterdam's red light district along with the cast and crew one evening, Janet Fielding was approached by a man who had mistaken her for one of the city's prostitutes.
  • Filming was allowed in Amsterdam so long as the story didn't involve drug smuggling, prostitution or diamond or art theft.
  • Colin Baker played Maxil not as a guest role, but as someone who thinks he's starring in his own series. As a result, John Nathan-Turner had to tell him that "it's called Doctor Who, not The Bloke Who's a Guard in the Background".
  • Colin Baker was a fan of the show and delighted to play a guest role, but was also disappointed that this seemingly meant that he could never play the Doctor.
  • When Colin Baker was offered the role of Maxil, he was doing a play in Brighton.
  • Colin Baker jokes that while filming the scene where Commander Maxil shoots the Doctor, he was gunning for Peter Davison's part. Davison claimed that Baker enjoyed the scene a bit too much.
  • Sarah Sutton ripped her trousers during the crypt scene.
  • Ian Collier described Omega's costume as one of the most uncomfortable experiences of his life.
  • Ian Collier got burned filming the explosives scenes. They used metal plates to cover the charges.
  • Peter Davison claimed that he was planning to use a dildo he purchased in Amsterdam as a weapon to kill Omega, but because they were running behind schedule, he didn't get a chance.
  • The cast found the Ergon costume laughable. Eric Saward claimed it was never described in the script and thought it was "lunatic" when he saw it. Johnny Byrne claimed it was a legitimate, "less successful attempt" at biosynthesis.
  • John Nathan-Turner never explained why he wanted Tegan back or left her behind. Eric Saward thought it was contrived, while Peter Davison thought it was a "ludicrous coincidence".
  • Sarah Sutton grew to dislike running around in Amsterdam, especially after three days of it.
  • Eric Saward claimed that John Nathan-Turner wanted to film in Amsterdam for no rhyme or reason and that all you could do is run around the streets.
  • The Ergon was envisaged as an assemblage of bones, inspired by the eponymous creature in Alien. Sadly, this effect, particuarly the inclusion of a pterodactyl skull (which Malcolm Harvey wore as a hat), did not come off as intended. With no time available to modify or replace it, the costume was judged a failure.
  • Although Richard Gregory of Imagineering was so happy with the Omega design that he wove his initials into the design on the chestplate, this costume proved problematic. Imagineering had incorporated servos to move the flaps covering Omega's mouth, but these proved to be so loud that they could not be used.
  • The Lord President was originally unnamed in the script. His role was given to Borusa.
  • Part of the decision to film in Amsterdam was that the BBC had recently shot Triangle there.
  • John Nathan-Turner encouraged costume designer Dee Robson to deviate from Omega's physical appearance in The Three Doctors, as he thought that it would further help preserve the surprise of the villain's identity, and could be justified by Omega's nigh-total control over mass and form in his anti-matter domain.
  • Eric Saward selected Johnny Byrne to write the serial having been impressed with The Keeper of Traken, unaware that Christopher H. Bidmead had largely re-written it.



  • Part one - 7.2 million viewers
  • Part two - 7.3 million viewers
  • Part three - 6.9 million viewers
  • Part four - 7.2 million viewers


  • New regular costumes for Nyssa and Tegan are seen for the first time in this story. (Although Tegan's new costume makes its debut here, Nyssa's is not seen until the following story, Snakedance. This myth derives from the fact that numerous publicity photographs of the two actresses wearing their new costumes were taken during Arc of Infinity's location shoot in Amsterdam. These photo shoots were made possible by the fact that Snakedance was completed before Arc of Infinity.)

Filming locations[]

  • Location shooting was done in Amsterdam in May of 1982:
  • Muntplein, Amsterdam
  • Herengracht, Amsterdam
  • Leidseplein, Amsterdam
  • Nieuwezijds Voorburgwal, Amsterdam
  • Zandpad, Amsterdam
  • Middenweg, Amsterdam, Netherlands
  • Prinsengracht, Amsterdam
  • Amstel Sluize, Amsterdam
  • Stationsplein, Amsterdam
  • Schiphol Airport, Amsterdam
  • Singel, Amsterdam
  • Lijnbaansgracht, Amsterdam
  • Sint Nicolaasstraat, Amsterdam
  • Amstelveld, Amsterdam
  • Frankendael House, Middenweg 172, Amsterdam
  • Amstel, Amsterdam
  • Dam Square, Amsterdam
  • BBC Television Centre (Studio 1), Shepherd's Bush, London

Production errors[]

to be added

If you'd like to talk about narrative problems with this story — like plot holes and things that seem to contradict other stories — please go to this episode's discontinuity discussion.


Home video and audio releases[]

DVD releases[]

This story was originally released in a double-pack with Time-Flight in Region 2 and 4 but released singly in Region 1.

The R2 and R4 cover art of this story and Time-Flight shows the "Peter Davison Years" as 1981-1984. All other Davison-era releases have claimed the years as 1982-1984 in deference to the January 1982 broadcast of Castrovalva. However, there is justification for calling the era 1981-1984, as that's the period of time Davison actually worked on the programme. Like Jon Pertwee, Davison fell victim to the BBC's decision to push back the premiere of his first series to the start of the new calendar year. Neither actor is generally credited for their first year on the job, making their eras appear a little shorter than they actually were. While Pertwee only filmed about half of Season 7 in 1969, almost everything of Season 19 was filmed in 1981. Indeed, Davison's first work on the series — his regeneration scene — had been filmed on 9 January 1981, almost a full year prior to the release of Castrovalva. Ironically, the only part of Davison's initial year not filmed in 1981 was Time-Flight, the only other DVD release to bear the claim of an era lasting from 1981-1984. All told, Davison's time in front of the cameras as the Doctor lasted from 9 January 1981 to 12 January 1984 — almost precisely the three-year tenure he had been advised by Patrick Troughton to undertake.


Special Features[]

  • Commentary by Peter Davison, Janet Fielding, Sarah Sutton and Colin Baker
  • Anti-Matter from Amsterdam - Presented by Sophie Aldred, this new documentary examines the making of Arc of Infinity. Featuring actors Peter Davison, Colin Baker and Sarah Sutton.
  • The Omega Factor - Writers and actors look at the character and motivation of the renegade Time Lord, Omega. Featuring co-creator Bob Baker, actors Stephen Thorne and Ian Collier
  • Deleted Scenes - Deleted scenes taken from time-coded viewing copies of the studio recordings and early edits.
  • Under Arc Lights - Behind-the-scenes action from the studio recording sessions.
  • CGI Effects - Viewers have the option to watch the story with eighteen of the original video effects replaced by brand new CGI versions.
  • Continuities - Original BBC1 continuity announcements for the story.
  • Photo Gallery - A selection of rare and previously unpublished photographs from the recording of this story.
  • Isolated Music - The option to watch the story with the original synchronous music only.
  • Radio Times Billings (PDF DVD-ROM)
  • 1983 Doctor Who annual (PDF DVD-ROM)
  • Production Subtitles - Subtitles provide the viewer with cast details, script development and other production information, offering further insight into the making of this story.
  • Coming Soon Trailer - The Time Warrior
  • Easter Egg: The Complete Davros Collection teaser trailer. To access this hidden feature, type the digits 1,9,7,5 on the second page of the Special Features menu.

Editing for the DVD release was completed by the Doctor Who Restoration Team.

It was released as issue 108 of Doctor Who DVD Files.

Box set[]

VHS releases[]

This story was first released in VHS episodic format in the UK March 1994, April 1994 in Australia, and September 1995 in the US, with a cover design by Pete Wallbank.

Digital releases[]

  • The story is available for streaming through BritBox in Canada & the US and Amazon Instant Video in the UK.

External links[]