The search for the Key to Time lands Dr. Who and Romana on a moon inhabited by swamp people---and a gigantic monster. Dr. Who: Tom Baker. Fenner: Philip Madoc. Romana: Mary Tamm. Thawn: Neil McCarthy. Dugeen: John Leeson. Rohm-Dutt: Glyn Owen.

The TARDIS arrives in the future on the planet Pluto where there are now six suns, a breathable atmosphere and a large industrial community. The Company controls the planet and exploits the workers, pays them a pittance and then taxes them on everything imaginable. The Doctor and Leela join forces with an underground band of rebels led by a man named Mandrel.

The TARDIS lands in the far future inside a spaceship orbiting the planet Sense-Sphere. The crew of the ship appear to be dead but then suddenly return to life.

On Skaro, Doctor Who and Romana (Lalla Ward) encounter their archenemies---the Daleks. Tyssan: Tim Barlow. Cmdr. Sharrel: Peter Straker. Agella: Suzanne Danielle. Lan: Toby Osoba. Veldan: David Yip.

Ships have been vanishing near the island on which The Master has been living in guarded exile.

A race of intelligent lizards seeks control of Earth.

The TARDIS lands in the far future inside a spaceship orbiting the planet Sense-Sphere. The crew of the ship appear to be dead but then suddenly return to life.

The Doctor encounters highly advanced reptiles. Monarch: Stratford Johns. Nyssa: Sarah Sutton. Persuasion: Paul Shelley. Enlightenment: Annie Lambert. Adric: Matthew Waterhouse.

The overlap between quantum reality and science fiction is discussed.

Cornell physics professor Dr. Mukund Vengalattore joins us to talk about Dr. Who's Weeping Angels and the strange overlap of quantum reality and science fiction. Dr. Vengalattore explains to Faith and Heather that, on the quantum level time actually runs forward and backwards, and for a rare instance the scientific world becomes "very wibbly-wobbly timey-whimey".