Another adventure for everyone's favourite Time Lord. The Doctor (Jon Pertwee) and Jo (Katy Manning) travel to Stangmoor prison to investigate a machine which can remove evil from the minds of criminals. However, the man behind the scheme - Professor Kellerman - is in fact the Doctor's arch-nemesis, the Master (Roger Delgado), and is planning to disrupt a United Nations peace conference. Inside the Master's machine is an alien parasite which can make people see their greatest fears, and is growing stronger all the time. Can the Doctor stop both the Master and the unearthly parasite?

The last adventure to star Jon Pertwee. To save the Universe, the Doctor must travel to the planet Metebelis Three, where he discovers an invasion plan of Earth by the Metebelis Spiders, under the leadership of the Great One. To save the planet the Doctor must absorb a lethal dose of radiation, triggering his third regeneration...

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.