Doctor Who Season 20

No Code Title Air Date Eps Exists
124 6D Arc of Infinity 03 Jan 1983 4 All
125 6E Snakedance 17 Jan 1983 4 All
126 6F Mawdryn Undead 01 Feb 1983 4 All
127 6G Terminus 15 Feb 1983 4 All
128 6H Enlightenment 01 Mar 1983 4 All
129 6J The King's Demons 15 Mar 1983 2 All
130 6K The Five Doctors 25 Nov 1983 1 All


In Terminus, Nyssa chooses to remain on Terminus trying to help the sick. In Mawdryn Undead, Turlough becomes a companion although he is in fact tasked with killing the Doctor by the Black Guardian.

Episode Details

Arc of Infinity

The Doctor's genetic bio-print is stolen from Gallifrey by a traitor, and passed to a mysterious anti-matter alien who then seeks to cross into the ordinary universe by bonding with the Doctor. To prevent this, the High Council sentences the Doctor to death! Can he escape and outwit the mysterious alien?


The evil Mara that possessed Tegan (in Kinda) controls her once again, diverting the TARDIS to the planet Manussa, original home of the Mara before it was banished into the outer darkness centuries ago. There, it steals the Great Crystal and tries to use it to cross back into the physical world! Can the Doctor save Tegan and defeat the Mara once again?

Mawdryn Undead

The TARDIS materializes on a huge spacecraft, concealed above the Earth. The Doctor and his companions are separated - the Doctor uses a transmat device to go down to Earth, while Nyssa and Tegan follow in the TARDIS. Arriving on Earth in 1977, Nyssa and Tegan meet up with the (retired) Brigadier and search for the Doctor. They are horrified when they meet a creature that claims to be the Doctor after an unsuccessful regeneration - locked into a continuous cycle of regenerations! But is it the Doctor?


The TARDIS materializes aboard a space ship full of lepers heading towards a promised cure on a space station called Terminus at the center of the Galaxy. Nyssa contracts the disease and the Doctor sets out to discover the true nature of the cure offered at Terminus...


The White Guardian warns the Doctor of a terrible peril, and sends the TARDIS to an Edwardian racing yacht. The Doctor is amazed when he realized that the yacht is, in fact, a space yacht and that the race is around the Solar system! The Captain, Straker, and his officers are Eternals - immortal beings with little imagination, racing for the ultimate prize of Enlightenment. The Buccaneer Captain of another ship, Wrack, is a servant of the Black Guardian and must be prevented from winning the race at all costs!

The King's Demons

The Doctor and his companions arrive at a medieval joust and are surprised to greeted warmly by King John, who calls them his demons. But a young Nobleman returns, having just left King John in London - this King must be an impostor! Then the Master makes an appearance and the Doctor's worst fears are confirmed...

The Five Doctors

The Doctor becomes ill as parts of his persona are Time Scooped - removed from time. He returns to Gallifrey, only to discover that a deadly game banned and derelict for centuries, has been reactivated. Soon he finds his other selves have also been summoned to assist him in tracing the culprit and tracking down the mysterious secret of Rassilon.