A three-man rocket crew are nearly done with their mission to Titan Base until a course change puts the rocket in the path of a strange cloud in space. By the time they arrive, they have come under the control of a sentient virus which threatens the galaxy. When the TARDIS picks up an emergency message, it flies into the cloud, infecting the Doctor. To save himself and others, he must undertake a dangerous journey.
The present day: just as the Fourth Doctor and Leela arrive in Fetchborough, England, Professor Fendelman prepares to experiment on a fossilized skull which science says should not exist. The skull is actually an artefact of the Fendahl, a god-like being who feeds on the life force of others. It has begun to awaken and kill. Worse yet, others seek to exploit the Fendahl's dreadful power.
Far in the distant future, Earth has become uninhabitable, forcing Mankind to colonise first Mars and then Pluto. No longer the coldest planet in the solar system, Pluto is now warmed by artificial suns. The Doctor, Leela and K9 arrive to discover the exploitation of the Megropolis people by the ruling elite, lead by the Collector. Deep in the Undercity, a small group of revolutionaries plot to overthrow the company and the Doctor is forced to fight the oppression of the people using Fire against Fire...
On the edge of the universe, the Doctor, Leela and K9 encounter a Minyan ship on an epic quest to find their race banks... but their people have encountered the Time Lords before...
The Doctor returns to Gallifrey, claims his rights and is inaugurated President. It soon turns out that he has led a group of aliens called Vardans to the planet to eradicate them completely. After they are destroyed, the Sontarans take their opportunity and follow them in their invasion until they are destroyed by the Doctor.
The Doctor and Romana learn the second segment of the Key to Time is on the planet Calufrax. Yet they arrive on a planet called Zanak, which has been hollowed out and fitted with hyperspace engines, allowing its insane, half-robot Captain to materialise it around smaller planets and plunder their resources.
Searching for the third segment to the Key to Time brings the Doctor and Romana to present-day Earth, where the travellers have to contend with stone circles, Druidic rituals and a not-so-mythical goddess known as the Cailleach.
The Doctor needs somewhere peaceful to recover from his traumatic regeneration. But the sanctuary of Castrovalva is not all it seems, as the Master will stop at nothing to gain his revenge over the Doctor...
Time-traveling bounty hunters find a doomed race-car driver in the past and bring him to 2009 New York, where his mind will be replaced with that of a terminally ill billionaire.
The Doctor and Leela must catch a killer on a vast mining ship run by robots and humans.
The cursed island of Fang Rock off the south coast of England is a place of rumour and tales of beasts from the sea. Three lighthouse men at the turn of the century face their fears when something comes from the sea to bring death to all it touches.
At the Tranquil Repose mortuary, the Doctor and Peri uncover a sinister plot to create a new breed of Daleks under the supervision of the mysterious Great Healer.
The Doctor and Peri arrive on Karfel, a planet ruled by fear where the enemies of its ruler, the despotic Borad, are banished into a time tunnel known as the Timelash.
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.
The Doctor discovers his old enemy the Master is intent on preventing Earth's industrial revolution in 19th century England. But the Rani, a second rogue Time Lord, has plans of her own...
An alien distress call draws the Doctor and Peri to Earth, 1985, where they uncover a Cyberman plot to change the course of history.
Captured in a time corridor, the Doctor and his companions are forced to land on 20th century Earth, diverted by the Doctor's oldest enemy - the Daleks. It is here the true purpose of the time corridor becomes apparent: after ninety years of imprisonment, Davros, the ruthless creator of the Daleks, is to be liberated to assist in the resurrection of his army. Not even the Daleks foresee the poisonous threat of their creator. Indeed, who would suspect Davros of wanting to destroy his own Daleks - and why? Only the Doctor knows the truth. Will he descend to Davros' level of evil to stop him?
Built for pleasure, Veronica 2030 is a love android from the future - but there's a problem with the programming... The robot has discovered the delicious sensation of human passion. The insatiable android must be stopped before she has a sexual short circuit.
As trouble brews on the space trading colony of Iceworld, the Doctor and Mel encounter their sometimes-ally Sabalom Glitz and a new friend who goes by the name "Ace".
The Rani has returned with another malicious scientific scheme. Taking advantage of the post-regenerative trauma the recently regenerated and unstable Doctor is going through, she hopes to achieve control of an approaching asteroid composed entirely of strange matter. Can the Doctor figure out he is being used for the Rani's evil experiment, and what is behind the door the Rani won't allow him past?