# Doctor Who season 20

The twentieth season of British science fiction television series Doctor Who began on 3 January 1983 with the story Arc of Infinity, and ended 16 March 1983 with The King's Demons. A 20th Anniversary special, "The Five Doctors", followed in November 1983. John Nathan-Turner produced this series, with Eric Saward script editing.

## Casting
### Main cast

* Peter Davison as the Fifth Doctor
* Sarah Sutton as Nyssa
* Janet Fielding as Tegan Jovanka
* Mark Strickson as Vislor Turlough
* Gerald Flood as Voice of Kamelion
* Richard Hurndall as the First Doctor
* Patrick Troughton as the Second Doctor
* Jon Pertwee as the Third Doctor
* Elisabeth Sladen as Sarah Jane Smith
* Carole Ann Ford as Susan Foreman
* Nicholas Courtney as Brigadier Lethbridge-Stewart
Peter Davison continues as the Doctor, accompanied by Tegan Jovanka (Janet Fielding). While Nyssa (Sarah Sutton) leaves halfway through the season in Terminus, Mark Strickson arrives as new companion Vislor Turlough in Mawdryn Undead. In the penultimate serial of the season, the shape-shifting android Kamelion (voiced by Gerald Flood) is invited aboard the TARDIS after the Doctor frees him from the Master. Kamelion accepts, though the character itself would only be seen again in Season 21's antepenultimate serial, Planet of Fire.
Past Doctors return for the 20th Anniversary special, with Patrick Troughton and Jon Pertwee appearing as the Second Doctor and Third Doctor. The First Doctor returns, played by Richard Hurndall as original actor William Hartnell died in 1975. Tom Baker was asked to return to play the Fourth Doctor but declined.
Past companions Elisabeth Sladen (Sarah Jane Smith), Nicholas Courtney (Brigadier Lethbridge-Stewart), Carole Ann Ford (Susan Foreman) return for the 20th Anniversary special, whilst Courtney also makes an appearance in Mawdryn Undead.

### Recurring actors

* Anthony Ainley as The Master
* Valentine Dyall as the Black Guardian
* Paul Jerricho as The Castellan
Anthony Ainley returns as the Master in The King's Demons and "The Five Doctors".
The Black Guardian, played by Valentine Dyall, also makes a return in Mawdryn Undead, Terminus and Enlightenment.
The Castellan, played by Paul Jerricho, appears in Arc of Infinity and reprises the role in "The Five Doctors".

### Guest stars

Additional companions Jamie McCrimmon (Frazer Hines), Zoe Heriot (Wendy Padbury), Liz Shaw (Caroline John) and Mike Yates (Richard Franklin) make cameos throughout the special.
David Banks makes his second of four appearances in the show in "The Five Doctors" as a Cyber-leader.
Colin Baker, who was subsequently cast as the Sixth Doctor, made his first appearance in Doctor Who as Commander Maxil in the season's first serial, Arc of Infinity, becoming the first actor to appear in the programme prior to taking on the role of the Doctor.

## Returning villains

Returning villains for the season are Omega (Arc of Infinity), The Black Guardian (Mawdryn Undead), (Terminus), (Enlightenment), Cybermen ("The Five Doctors") and The Mara (Snakedance). A lone Dalek and a lone Yeti appear briefly in "The Five Doctors". The Master (Doctor Who) is the main villain in ‘’The King’s Demons’’ and also appears in The Five Doctors.

## Serials

To commemorate the twentieth season, the stories in this season involve the return of characters or villains seen in previous seasons. This season was broadcast twice weekly on Tuesday and Wednesday evenings on BBC1. It includes The Black Guardian Trilogy, consisting of the serials Mawdryn Undead, Terminus and Enlightenment and involving the arrival of Turlough, the departure of Nyssa and a single guest appearance from Brigadier Lethbridge-Stewart. Overall, these serials form a rough twelve-part epic.
Although "The Five Doctors" was broadcast more than eight months after Part 2 of The King's Demons, which was the last regular story of the season, it is usually included as part of Season 20.
| No. story | No. in season | Serial title | Episode titles | Directed by | Written by | Original release date | Prod. code | UK viewers (millions) | AI |
| 123 | 1 | Arc of Infinity | "Part One" | Ron Jones | Johnny Byrne | 3 January 1983 (1983-1-3) | 6E | 7.2 | 69 |
| 123 | 1 | Arc of Infinity | "Part Two" | Ron Jones | Johnny Byrne | 5 January 1983 (1983-1-5) | 6E | 7.3 | 70 |
| 123 | 1 | Arc of Infinity | "Part Three" | Ron Jones | Johnny Byrne | 11 January 1983 (1983-1-11) | 6E | 6.9 | 67 |
| 123 | 1 | Arc of Infinity | "Part Four" | Ron Jones | Johnny Byrne | 12 January 1983 (1983-1-12) | 6E | 7.2 | 66 |
| The Doctor's bio-data extract is stolen from the Matrix on Gallifrey. Soon after, a being from an anti-matter universe begins to genetically bond with the Doctor. He and Nyssa return to Gallifrey, only for the High Council to order his execution – while on Earth, unbeknownst to her friends, Tegan's search for her missing cousin in Amsterdam is somehow tied into the events as well. It is left to Nyssa to uncover the identity of a traitor on the High Council, and to unveil the enemy manipulating the Doctor – an entity who has long thirsted for revenge against both the Doctor and the Time Lords themselves. ||||||||||
| 124 | 2 | Snakedance | "Part One" | Fiona Cumming | Christopher Bailey | 18 January 1983 (1983-1-18) | 6D | 6.7 | 65 |
| 124 | 2 | Snakedance | "Part Two" | Fiona Cumming | Christopher Bailey | 19 January 1983 (1983-1-19) | 6D | 7.7 | 66 |
| 124 | 2 | Snakedance | "Part Three" | Fiona Cumming | Christopher Bailey | 25 January 1983 (1983-1-25) | 6D | 6.6 | 67 |
| 124 | 2 | Snakedance | "Part Four" | Fiona Cumming | Christopher Bailey | 26 January 1983 (1983-1-26) | 6D | 7.4 | 67 |
| The Mara once again takes control of Tegan's mind and compels her to direct the TARDIS to Manussa, seat of its once-mighty empire. Generations earlier, the Mara was driven off Manussa with the use of the Great Crystal, a device which enhances its users' mental abilities. Now, the Mara intends to use the Crystal to return to power. It is up to the Doctor to unearth the terrible origins of the Mara, and seek out the one man who can show him how to defeat the Mara in psychic combat. ||||||||||
| 125 | 3 | Mawdryn Undead | "Part One" | Peter Moffatt | Peter Grimwade | 1 February 1983 (1983-2-1) | 6F | 6.5 | 67 |
| 125 | 3 | Mawdryn Undead | "Part Two" | Peter Moffatt | Peter Grimwade | 2 February 1983 (1983-2-2) | 6F | 7.5 | 70 |
| 125 | 3 | Mawdryn Undead | "Part Three" | Peter Moffatt | Peter Grimwade | 8 February 1983 (1983-2-8) | 6F | 7.4 | 67 |
| 125 | 3 | Mawdryn Undead | "Part Four" | Peter Moffatt | Peter Grimwade | 9 February 1983 (1983-2-9) | 6F | 7.7 | 68 |
| An alien named Turlough lives in secret amongst boys at an English boarding school where the Brigadier is now teaching maths. He is contacted by the Black Guardian, who wants him to kill the Doctor. The TARDIS, meanwhile, has brought the Doctor, Nyssa and Tegan to a space station trapped in a warp ellipse. It serves as a prison for a team of scientists led by Mawdryn, who tried to steal the secrets of the Time Lords and instead placed him and scientists in a state of perpetual regeneration. It is up to the Doctor to find some way to help Mawdryn, but doing so may cost him his remaining regenerations. ||||||||||
| 126 | 4 | Terminus | "Part One" | Mary Ridge | Stephen Gallagher | 15 February 1983 (1983-2-15) | 6G | 6.8 | 65 |
| 126 | 4 | Terminus | "Part Two" | Mary Ridge | Stephen Gallagher | 16 February 1983 (1983-2-16) | 6G | 7.5 | 67 |
| 126 | 4 | Terminus | "Part Three" | Mary Ridge | Stephen Gallagher | 22 February 1983 (1983-2-22) | 6G | 6.5 | 64 |
| 126 | 4 | Terminus | "Part Four" | Mary Ridge | Stephen Gallagher | 23 February 1983 (1983-2-23) | 6G | 7.4 | 67 |
| Turlough's sabotage causes the TARDIS to make an emergency landing on a space station called Terminus, where victims of the horrible, virulent Lazar disease go to die. The Doctor discovers that Terminus is powered by two enormous engines, one of which exploded long ago, an event which instigated the Big Bang and the creation of the universe. Now the other engine is on the brink of detonating as well – an event which will have cataclysmic consequences for the cosmos. ||||||||||
| 127 | 5 | Enlightenment | "Part One" | Fiona Cumming | Barbara Clegg | 1 March 1983 (1983-3-1) | 6H | 6.6 | 67 |
| 127 | 5 | Enlightenment | "Part Two" | Fiona Cumming | Barbara Clegg | 2 March 1983 (1983-3-2) | 6H | 7.2 | 65 |
| 127 | 5 | Enlightenment | "Part Three" | Fiona Cumming | Barbara Clegg | 8 March 1983 (1983-3-8) | 6H | 6.2 | 68 |
| 127 | 5 | Enlightenment | "Part Four" | Fiona Cumming | Barbara Clegg | 9 March 1983 (1983-3-9) | 6H | 7.3 | 70 |
| Under the failing influence of the White Guardian, the TARDIS materialises on what appears to be an Edwardian racing yacht. It is soon revealed to be a cleverly disguised spacecraft, competing in an interplanetary race. The competitors are Eternals, immortal beings incapable of imagination or creative thought, while the crew are mortals, upon whose minds the Eternals draw for inspiration. The prize in the race is Enlightenment, offered up by the Black and White Guardians. One of the Eternals, the vicious Captain Wrack, is in league with the Black Guardian, however, and will stop at nothing to win. ||||||||||
| 128 | 6 | The King's Demons | "Part One" | Tony Virgo | Terence Dudley | 15 March 1983 (1983-3-15) | 6J | 5.8 | 65 |
| 128 | 6 | The King's Demons | "Part Two" | Tony Virgo | Terence Dudley | 16 March 1983 (1983-3-16) | 6J | 7.2 | 63 |
| The Doctor, Tegan and Turlough find themselves in 1215 England. They arrive at the castle of Ranulf Fitzwilliam, and are astounded to find King John there too, especially since he is supposed to be in London at the same time, involved in the events which will lead to the signing of Magna Carta. The time travellers discover that the King is not who he claims – in fact, he is a shapechanging robot named Kamelion under the influence of the Master, who is trying to irreversibly pervert the course of Earth's history. ||||||||||
| Special ||||||||||
| 129 | – | "The Five Doctors" | N/A | Peter Moffatt | Terrance Dicks | 25 November 1983 (1983-11-25) | 6K | 7.7 | 75 |
| While the Fourth Doctor and Romana are trapped in a time eddy, the First, Second, Third and Fifth Doctors – together with many of their companions – are lured by a mysterious figure to the forbidden Death Zone on Gallifrey. There they make their way towards the Dark Tower in which Rassilon is entombed, encountering a number of their deadliest foes en route. When the Fifth Doctor finds a way to teleport himself to the Capitol, however, he uncovers evidence of a traitor on the High Council. All are embroiled in the Game of Rassilon, whose prize is immortality itself. ||||||||||

## Broadcast

The entire season (including the show's 20th anniversary special "The Five Doctors") was broadcast from 3 January to 25 November. Transmission moved to Tuesdays and Wednesdays, except for the first episode of Arc of Infinity.

## Home media
### VHS releases

| Season | Story no. | Serial name | Number and duration of episodes | UK release date | Australia release date | USA/Canada release date |
| 20 | 123 | Arc of Infinity | 4 x 25 mins | March 1994 | April 1994 | September 1995 |
| 20 | 124 | Snakedance | 4 x 25 mins | December 1994 | February 1995 | September 1996 |
| 20 | 125 | Mawdryn Undead | 4 x 25 mins | November 1992 | May 1993 | February 1994 |
| 20 | 126 | Terminus | 4 x 25 mins | February 1993 | June 1993 | May 1994 |
| 20 | 127 | Enlightenment | 4 x 25 mins | February 1993 | May 1993 | August 1994 |
| 20 | 128 129 | The King's Demons "The Five Doctors" - Special Edition | 2 x 25 mins 1 x 100 mins | November 1995 2 x VHS | July 1997 2 x VHS | February 1997 2 x VHS |
| 20 | 129 | "The Five Doctors" | 1 x 90 mins | September 1985 July 1990 | May 1988 | March 1989 |

### Betamax releases

| Season | Story no. | Serial name | Number and duration of episodes | UK release date | Australia release date | USA/Canada release date |
| 20 | 129 | "The Five Doctors" | 1 x 90 mins | September 1985 | — | — |

### Laserdisc releases

| Season | Story no. | Serial name | Number and duration of episodes | UK release date | Australia release date | USA/Canada release date |
| 20 | 130 | "The Five Doctors" | 1 × 90 min. | — | 24 August 1994 | — |

### DVD and Blu-ray releases

All releases are for DVD unless otherwise indicated:
* $^{(B)}$ indicates a Blu-ray release
| Season | Story no. | Serial name | Number and duration of episodes | R2 release date | R4 release date | R1 release date |
| 20 | 123 | Arc of Infinity | 4 × 25 min. | 6 August 2007 | 5 September 2007 | 6 November 2007 |
| 20 | 124 | Snakedance | 4 × 25 min. | 7 March 2011 | 7 April 2011 | 12 April 2011 |
| 20 | 125–127 | Mawdryn Undead Terminus Enlightenment | 12 × 25 min. 1 × 75 min. | 10 August 2009 | 5 November 2009 | 3 November 2009 |
| 20 | 128 | The King's Demons | 2 × 25 min. | 14 June 2010 | 5 August 2010 | 7 September 2010 |
| 20 | 129 | "The Five Doctors" (Special Edition) | 1 × 100 min. | 1 November 1999 | 9 October 2000 | 11 September 2001 |
| 20 | 129 | "The Five Doctors" (25th Anniversary Edition) | 1 × 90 min. 1 × 100 min. | 3 March 2008 | 5 June 2008 | 5 August 2008 |
| 20 | 123–129 | Complete Season 20 | 22 × 25 min. 1 × 90 min. 1 × 100 min. | 18 September 2023 $^{(B)}$ | 24 July 2024 $^{(B)}$ | 4 June 2024 $^{(B)}$ |
* ↑ The Five Doctors was first broadcast in the United States on 23 November 1983, the actual date of the programme's 20th anniversary.
* ↑ Only available as part of the Time-Flight/Arc of Infinity box set in Regions 2 and 4. Only available individually in Region 1.
* ↑ Only available as part of the Mara Tales box set in Regions 2 and 4. Only available individually in Region 1.
* ↑ Known collectively as The Black Guardian Trilogy. Each serial comprises four episodes.
* ↑ The 75-minute long episode is an Enlightenment Special Edition
* ↑ Only available as part of the Kamelion Tales box set in Regions 2 and 4. Only available individually in Region 1.
* 1 2 3 "Special edition" of "The Five Doctors" with restored footage and new special effects
* 1 2 Broadcast version of "The Five Doctors"
* ↑ Released as Doctor Who: The Collection – Season 20 in Region B. Released as Doctor Who – Peter Davison: Complete Season Two in Region A.

## In print

| Season | Story no. | Library no. | Novelisation title | Author | Hardcover release date | Paperback release date | Audiobook release date |
| 20 | 123 | 80 | Arc of Infinity | Terrance Dicks | 21 July 1983 | 20 October 1983 | 3 June 2021 |
| 20 | 124 | 83 | Snakedance | Terrance Dicks | 21 January 1984 | 19 April 1984 | 6 February 2025 |
| 20 | 125 | 82 | Mawdryn Undead | Peter Grimwade | 18 August 1983 | 12 January 1984 | 5 July 2018 |
| 20 | 126 | 79 | Terminus | Stephen Gallagher (as John Lydecker) | 16 June 1983 | 15 September 1983 | 1 August 2019 |
| 20 | 127 | 85 | Enlightenment | Barbara Clegg | 16 February 1984 | 24 May 1984 | 3 September 2020 |
| 20 | 128 | 108 | The King's Demons | Terence Dudley | 20 February 1986 | 10 July 1986 | 5 May 2016 |
| 20 | 129 | 81 | The Five Doctors | Terrance Dicks | 24 November 1983 | 24 November 1983 | 2 November 2017 |
* ↑ Number in Target's Doctor Who Library, if applicable
* ↑ Published by Target's parent companies (Allen Wingate, W. H. Allen, BBC Books) unless otherwise indicated
* ↑ Published by Target Books (or by BBC Books under the Target Collection umbrella) unless otherwise indicated
* ↑ Unabridged from BBC Audio/AudioGo unless otherwise indicated