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?

Another adventure for everyone's favourite Time Lord. The arrival on Earth of a UFO brings with it the Axons - golden-skinned aliens who offer the gift of Axonite to mankind. The Doctor (Jon Pertwee) is suspicious, especially when he discovers that his old enemy the Master (Roger Delgado) is on board the Axon craft.