A collection of classic Doctor Who episodes featuring Tom Baker and Jon Pertwee in the role of the Doctor. In the four-parter 'The Horns of Nimon', the Skonnon ships have returned to the skies of Aneth, demanding tribute. But as the final consignment is being taken to Skonnos, an accident forces the ship off course. In the six-parter 'The Time Monster', a new invention to transport matter through time creates a number of disturbing distortions in the temporal fabric. The Doctor (Jon Pertwee) investigates, and soon finds himself up against his nemesis, The Master, in a battle to control a powerful sacred crystal. In the four-parter 'Underworld', the TARDIS lands the Doctor (Tom Baker) in a Minyan spaceship that is on a quest to find the Minyan race banks stored in a missing ship known as the P7E. They eventually find what they are looking for in a cave system at the centre of a newly-formed planet. But the P7E's computer has ideas of its own, and doesn't look kindly upon its new visitors.