Season 20

(4 episodes)

Travelling with Nyssa in the TARDIS, the Doctor is attacked by a malign entity, a being of pure anti-matter seeking to cross the dimensions and bond with the Doctor. Although the invader is successfully repelled, the TARDIS is immediately recalled to Gallifrey, where the High Council of Time Lords sentence the Doctor to be executed to prevent any further attempts at bonding. It seems there is a traitor on Gallifrey. And what links this renegade with the disappearance of Tegan's cousin in Amsterdam? Two fates intertwined must battle for the future of the entire universe...

Written by Johnny Byrne

(4 episodes)

Tegan falls once more under the influence of the Mara and directs the TARDIS to the planet Manussa. There the Federator‘s son Lon and his mother Tanha are preparing for a ceremony to celebrate the banishment of the Mara five hundred years earlier. But the threat of the Mara endures, and it's up to the Doctor to defeat it.

Written by Christopher Bailey

(4  episodes)

The Black Guardian recruits a young man named Turlough to assassinate the Doctor. Although outwardly an ordinary pupil at a boys' private boarding school, Turlough is in fact an alien who believes that the Guardian will return him home if he succeeds.

Written by Peter Grimwade

(4 episodes)

The TARDIS attaches itself to a space liner after Turlough, still under the Black Guardian's influence, damages its controls. The Doctor and Nyssa meet two space pirates, Kari and Olvir, who have come on board the liner in search of plunder, while Tegan and Turlough get lost in the infrastructure.

Written by Steve Gallagher

(4 episodes)

The White Guardian warns of impending danger and directs the TARDIS to what appears to be an Edwardian sailing yacht, the SS Shadow, but is actually one of a number of spaceships taking part in a race through the solar system, the prize being Enlightenment.

Written by Barbara Clegg

(2 episodes)

England, March 1215. King John is visiting the castle of Sir Ranulph Fitzwilliam. The arrival of the TARDIS disturbs a medieval joust, but the Doctor and his companions are proclaimed to be friendly demons by the King, who seems strangely interested in their "blue engine." It soon becomes clear that neither King John or his Champion, Sir Gilles Estram, are who they pretend to be. One of the Doctor's oldest and deadliest enemies threatens the future of democracy on Earth, and he must be stopped!

Written by Terence Dudley

The Doctor's past incarnations are being snatched out of time and transported to the Death Zone on Gallifrey, where they are reunited with some old friends and pitted against their deadliest enemies in the Game of Rassilon. Someone is manipulating the Doctor and his companions in order to claim the most ancient and powerful secret of the Time Lords... but can they survive the challenges and uncover the traitor before it is too late?

Written by Terrance Dicks