The Doctor, Romana and K9 land on the planet Zanak in their search for the second segment to the Key to Time. Tom Baker. Romana: Mary Tamm. Captain: Bruce Purchase.

The Doctor arrives on Gallifrey, where he is accused of the assassination of the Time Lord President. Investigating with the aid of Co-ordinator Engin and Castellan Spandrell, he discovers that this is part of a plot hatched by his old adversary the Master.

The Doctor and Romana are enjoying a holiday in Paris, 1979, when they become aware of a fracture in time. During a visit to the Louvre to see da Vinci's Mona Lisa, the Doctor purloins from a stranger, Countess Scarlioni, a bracelet that is actually an alien scanner device.

The Doctor, Romana and K9 are caught between savage beasts and deadly weapons. Dr. Who: Tom Baker. Sholakh: Robert Keegan. Romana: Mary Tamm. Voice of K9: John Leeson.

The Doctor, Romana and K9 are led by the tracer to the Nine Travellers in present day England.

The TARDIS becomes trapped underground in a mining explosion where a million year old fossilized being seems to be possessing the Doctors' companion Sarah.

The TARDIS arrives on a planet where a savage tribe called the Sevateem worship a god called Xoanon. The Doctor discovers that Xoanon is in fact a spaceship computer that he tried to repair at some point in his past and inadvertently drove mad by giving it a multiple personality.

On a holiday in Paris, the Doctor (Tom Baker) and Romana uncover a plot to steal the Mona Lisa. Julian Glover. Duggan: Tom Chadbon. Countess: Catherine Schell. Kerensky: David Graham.

The Doctor and Romana uncover a drug-smuggling operation and set out to find the source of Zip, the most dangerous drug in the universe. Lalla Ward. Rigg: David Daker. Della: Jennifer Lonsdale. Tryst: Lewis Fiander.

Freddie (Sir Ian McKellen) and Stuart (Sir Derek Jacobi) shop for a new coat for Freddie for his fan club event. Since the coat is more expensive than they'd expected, Stuart finds a way of secretly raising some cash. Meanwhile, Ash (Iwan Rheon) seeks Freddie and Stuart's advice to win back his ex-girlfriend. (2 of 7)

The Doctor battles the Master and a renegade Time Lady named Rani, who are wreaking havoc on a 19th-century mining community. The Master: Anthony Ainley. Peri: Nicola Bryant. Jack Ward: Peter Childs.

Two incarnations of the Time Lord (Colin Baker, Patrick Troughton) join to stop Dastari and Chessene from performing dangerous experiments in time. Dastari: Laurence Payne. Chessene: Jacqueline Pearce. Peri: Nicola Bryant. Jamie: Frazer Hines.

Part 1. The Doctor finds an unusual hiding place.

Part 2. Smith and Jones are under siege.

When people start to disappear, a young woman finds cryptic messages bleeding through from a mysterious stranger called the Doctor.

Capt. Jack storms back into the Doctor's life; the Tardis travels to the end of the universe.

Part 1. Harry Saxon becomes Prime Minister, but has dark ambitions.

Part 2. With The Doctor imprisoned by The Master, Martha endeavors to save the world.

Kylie Minogue joins Doctor Who to play Astrid, a waitress on a doomed spaceship that eerily resembles the Titanic. When a meteor hits, Astrid and The Doctor must protect the survivors from and prevent the whole ship from crashing to Earth.

Donna is determined to find the Doctor, even if it means braving Miss Foster and her hordes of Adipose.

The Doctor and Donna visit Pompeii in AD 79, on the eve of the eruption of Mount Vesuvius.

The Doctor takes Donna to her first alien world, but the Ood-Sphere reveals some terrible truths about the human race.

Part 1. Sontaran warriors set their sights on the Earth and its inhabitants.

Part 2. As poison gas suffocates the Earth's population, the Doctor and UNIT team members work to eliminate the threat.

The overlap between quantum reality and science fiction is discussed.