A husband and wife team are hired to protect an eccentric millionaire from an assassin but a series of murders follows.

An estate agent arranges to meet a couple for a viewing at a flat.

A race of giant Gastropods has taken over the planet Jaconda. Their leader, Mestor, now intends to cause an enormous explosion in order to spread his people's eggs throughout the galaxy, and he kidnaps juvenile twin geniuses from Earth to work out the necessary mathematical equations. Space fighters led by Lieutenant Hugo Lang are dispatched to get the twins back, but they come under attack and Lang is the sole survivor when his ship crashes on the asteroid Titan III. A newly regenerated Doctor and Peri become involved and help Jaconda's elderly former ruler Professor Edgeworth, who is really a Time Lord named Azmael, to defeat Mestor and free the planet's bird-like indigenous people from the gastropods' reign of terror. Azmael, however, sacrifices his life in the process.

Suddenly gripped by a memory of being executed in his second incarnation, the Sixth Doctor travels to Seville to save his past self and ensure his own existence in his present.

In 17th century England, the Doctor and itinerant thespian Richard Mace uncover a plot by a crew of criminal Terileptils to wipe out humanity.

A warp ellipse draws the TARDIS off course. The Fifth Doctor's companions are separated from him not in space, but in time, and he has to deal with a treacherous schoolboy named Turlough. But why does the Doctor's old friend, the Brigadier, not remember him at all?

Still trapped in E-Space, the Doctor, Romana, Adric and K9 encounter a medieval civilisation dominated by the Three Who Rule, vampires who govern from their mighty castle.

Daniel is about to marry a woman 30 years his senior. The woman begins to suspect that he is after her money.

A couple invite an old school friend for a reunion dinner, it is during the conversation (with the friend now an eminent surgeon) the couple come to the stark realization that their son is showing symptoms of a looming brain tumour.

Many incarnations of the Doctors and their old companions are taken out of time and deposited in the Death Zone on Gallifrey. There, they must battle the Master, Daleks, Cybermen and Yeti in order to reach the Dark Tower and discover the Tomb of Rassilon.