Another adventure for the intrepid space/time traveller. The Doctor (Tom Baker) has returned the TARDIS to his home planet of Gallifrey, but why has he forbidden Leela (Louise Jameson) to accompany him? Why, upon claiming the Presidency, does he expel every senior Time Lord to the outer wastes? And what plan is he hatching with the hostile Vardans? The only people he seems to have taken into his confidence are K9 and Chancellor Borusa, but whatever game the Doctor is playing, he has reckoned without the return of an old foe... This story marks the departure from the series of Leela and K9 Mark 1.

The longest 'Doctor Who' story ever. The Doctor (Colin Baker) is put on trial by his people the Time Lords for interference in the affairs of others; three segments of his past and future are presented as evidence. 'The Mysterious Planet' shows the Doctor and Peri (Nicola Bryant) in a battle with a megalomaniac machine on the planet Ravalox, but what are the mysterious 'secrets' it protects? 'Mindwarp' shows the Doctor apparently betraying Peri to the vile Sil (Nabil Shaban) and the Mentors - can the Matrix be falsifying the evidence against the Doctor? In his defence he presents 'Terror of the Vervoids', a future story where the Earth is threatened by evil plant life forms. In the final two episodes, 'The Ultimate Foe', the Doctor learns the truth about his prosecuting counsel, the Valeyard (Michael Jayston), and has to enter the Matrix to battle for his remaining lives. This was Colin Baker's last story as the Doctor.

Feature-length episode to celebrate the 20th anniversary of the long-running sci-fi series. All five Doctors (Peter Davison, Patrick Troughton, Jon Pertwee, Richard Hurndall and Tom Baker) and many of their old companions are taken out of time and deposited in the Death Zone on Gallifrey. There they must battle not only the Master, but Daleks, Cybermen and Yeti in order to reach the Dark Tower and discover the Tomb of Rassilon. This special edition includes new special effects and extra footage not included in the original broadcast.