UNIT are called in when top secret plans and valuable equipment is stolen from high security establishments. The newly regenerated Doctor suggests that the thief may not be human.

Using the deadly disintegrator weapon, the robot steals the destructor codes. Harry Sullivan is sent to infiltrate Think Tank to discover the truth.

Sealed inside an underground bunker, Miss Winters issues her demands to the world’s leaders, threatening a devastating nuclear strike if her demands are not met.

The Doctor races to avert a nuclear holocaust. The robot, distraught over killing its creator, takes Sarah hostage and goes on a rampage.

The TARDIS arrives in the far future on the Ark space station where the survivors of mankind are in hibernation. Sarah is accidentally placed in suspended animation.

When the Doctor restores the power to the Ark, the humans begin to revive. But the station has been invaded by the giant insectoid Wirrn.

The Doctor subjects himself to a dangerous experiment so that he can access the memories of the dead Wirrn Queen. Elsewhere, the larvae Wirrn are pupating into their adult form.

The mutated Noah has now fully transformed into a Wirrn adult and intends to allow the Wirrn to devour the sleeping humans, absorbing their memories and knowledge.

The Doctor, Harry and Sarah find Earth is an empty wilderness. They meet a group of stranded human colonists who are being hunted by a robot and experimented upon by its master.

Sarah has been captured by the Sontaran, Field Major Styre who is conducting cruel experiments on the captured humans, paving the way for a full-scale invasion.

The Time Lords send the Doctor, Sarah and Harry to Skaro at a point in time shortly before the creation of the Daleks. The Doctor's mission is to destroy his greatest enemy.

The Doctor finds that some of Davros’s fellow Kaleds are unhappy with the development of the Daleks. Sarah is forced to load a Thal war rocket with radioactive explosives.

The Doctor informs the Kaled government of Davros’s experiments and they move to shut down the bunker. But Davros is one step ahead and prepares to take drastic action.

When the Kaled dome is destroyed by the Thals’ rocket, the war appears to be over and the Thals rejoice at their victory. But then, the Daleks appear and a massacre begins.

With Harry and Sarah his prisoners, Davros interrogates the Doctor, forcing him to reveal the future of the Daleks so that he can learn from their defeats to make them stronger.

The Kaled scientific elite move to prevent the development of the Daleks while the Doctor prepares to destroy them forever. But is it already too late?

The Doctor, Sarah and Harry return to Nerva, but at an earlier point in time. The crew are dying from a space plague but the Doctor suspects a survivor may be responsible.

Sarah is the latest victim of the space plague and the only way to cure her is by transmatting her down to the surface of the mysterious planetoid, Voga.

The Cybermen who are intent on destroying Voga. The Doctor and two of the Nerva crew become walking bombs which they Cybermen will detonate once they reach their target.

Their plan to blow up Voga thwarted, the Cybermen intend to crash Nerva into the planet. Vorus is almost ready to launch his rocket at Nerva, but Sarah is still trapped on board.

The Doctor, Sarah and Harry return to Earth to help the Brigadier discover what is causing the destruction of oil rigs off the coast of Scotland.

Sarah is attacked by a Zygon disguised as Harry who is a prisoner on the Zygon spaceship. The Doctor falls into a trap and is hunted down by the giant Skarasen.

The Doctor and Sarah find their way into the Zygon spaceship at the bottom of Loch Ness while the Brigadier prepares to force it to the surface with depth charges.

The Zygon warlord, Broton, disguised as the Duke of Forgill, intends to use the Skarasen to attack the World Energy Conference in London.

The TARDIS takes the Doctor and Sarah to the planet Zeta Minor on the edge of the universe. An unseen menace has wiped out an Morestran expedition and haunts the alien jungle.

The Doctor and Sarah are held responsible for the deaths on Zeta Minor, but the Doctor knows that the real culprit comes from the mysterious universe of antimatter.

Lost in the universe of antimatter, the Doctor communes with the creature and makes a bargain. Sarah discovers Professor Sorensen’s dark secret which threatens to overwhelm him.

Unable to escape, the Morestran probe is being pulled back to the surface of Zeta Minor. Onboard the ship, the Doctor and Sarah are hemmed in by anti-men.

The TARDIS lands in 1911. In the grounds of the Old Priory, Egyptian mummies are walking and the Doctor and Sarah discover that an ancient and powerful evil is manifesting itself.

The Doctor, Sarah and Laurence Scarman are being hunted down by Sutekh’s robot mummies. The Doctor has a plan disrupt Sutekh’s control signal, but will it work?

The mummies are building a rocket to fire at the pyramid on Mars which will release Sutekh. The Doctor is determined to destroy the rocket but is Sutekh’s will too strong?

Inside the pyramid on Mars, the Doctor and Sarah must solve puzzles and escape traps to prevent Sutekh’s release from his imprisonment – but are they too late?

The TARDIS arrives back on Earth but all is not as it seems as the Doctor and Sarah are attacked by mysterious space suited figures and discover that the dead are walking..

The TARDIS arrives back on Earth but all is not as it seems as the Doctor and Sarah are attacked by mysterious space suited figures and discover that the dead are walking.

The Kraals intend to invade Earth by stowing away aboard Crayford’s rocket as it returns home. The Doctor learns Styggron’s plan is to wipe out all life on the planet.

The Doctor and Sarah are desperate to warn UNIT of the Kraal’s invasion, but nobody will believe them. The Kraal’s release their android duplicates, including one of the Doctor.

The Doctor and Sarah arrive on the planet Karn. There they take shelter in the castle of Dr Solon who is secretly hiding the living brain of the Time Lord criminal, Morbius.

The Doctor is a prisoner of the Sisterhood of Karn who intend to burn him at the stake. Sarah hurries to the Doctor’s rescue but pays the price for her efforts.

Sarah has been blinded and the Doctor asks the Sisterhood for help. Morbius, fearful that the Time Lords have tracked him down, tells Solon to install his brain in a new body.

Morbius, housed in a terrifying new body, lives and breathes once more and the Doctor is forced to challenge his foe to a deadly mental duel which only one of them will survive.

When the Doctor learns of the discovery of two alien seed pods in the Antarctic, he and Sarah rush to investigate. But they are too late. A man is already turning into a Krynoid.

The Krynoid is on the loose in the arctic. Scorby and Keeler have been sent to steal the alien pod and are willing to resort to murder to cover their tracks.

The Doctor and Sarah track down the remaining Krynoid pod to the estate of Harrison Chase. The millionaire botanist intends use the pod to change a human victim into a Krynoid.

Keeler has been infected by the alien pod and is transforming into a Krynoid. Chase refuses to listen to the Doctor’s warning and throws him into a compost machine.

The Krynoid demands that the Doctor be surrendered to it. But the Doctor escapes to seek help. Sarah and Scorby, still trapped on the estate, battle against the living plants.

The Doctor, Sarah and Scorby are hunted down by the mad Harrison Chase. Outside the Krynoid prepares to germinate, sending its deadly seed pods out across the land.

The Doctor lands in Renaissance Italy unaware he has brought an alien energy with him.

The Mandragora energy joins forces with the secret Brotherhood of Demnos.

Tempted by the power offered by Mandragora, Hieronymous plots to eliminate his enemies.

As the leading scholars of the era assemble for the masque, Mandragora prepares to attack.

Sarah becomes possessed by the fossilized stone hand of an alien, Eldrad.

At a nuclear power station, the stone hand comes to life and seeks access to the reactor.

The hand has regrown into Eldrad, who demands that the Doctor return her to Kastria.

The Doctor and Sarah suspect that Eldrad has not been entirely honest with them.

The Doctor returns to Gallifrey and races to prevent a tragedy.

The Time Lord president has been assassinated and the Doctor is the prime suspect.

The Doctor enters the virtual world of the Matrix hoping to track down the Master.

The Master makes his final bid to release the devastating power of the Time Lords.

The Doctor arrives on an alien world and is accused of being 'the evil one'.

The Sevateem prepare to launch an attack to free their god, Xoanon.

The Doctor discovers the terrible truth about Xoanon and realises that he is to blame.

The insane computer Xoanon refuses the Doctor's help and prepares to destroy the planet.

The TARDIS takes the Doctor and Leela to a huge sandminer on an alien world.

The Doctor and Leela are blamed for the murder of one of the sandminer's crew.

Taren Capel is using the robots to carry out the murders.

As the robots close in, the Doctor and Leela join forces with the crew to fight back.

[Language and portrayal may cause offense.] The Doctor and Leela arrive in Victorian London where many young women have disappeared.

[Language and portrayal may cause offense.] The Doctor and Leela take refuge at the home of Professor Litefoot.

[Language and portrayal may cause offense.] Weng-Chiang is desperate to recover his lost time cabinet.

[Language and portrayal may cause offense.] The Doctor plans to confront Li H'sen Chang, but Greel no longer needs his servant.

[Language may cause offense.] Magnus Greel has recovered his lost time cabinet and the Doctor hurries to track him down.

[Language may cause offense.] The Doctor tracks Greel to his secret hideaway at the House of the Dragon.

The TARDIS lands on Fang Rock island at the start of the 20th century. There the Doctor and Leela discover a lighthouse keeper has been killed and a creature is at large.

A thick fog surrounds Fang Rock and a ship is wrecked. The survivors take shelter in the lighthouse but all are in deadly peril from the alien menace that stalks the island.

The Doctor seals the survivors inside the lighthouse but discovers that he may unwittingly have trapped the creature inside with them.

As the alien Rutan picks off the remaining humans one by one, the Doctor devises a desperate plan to defeat the alien and repel the approaching Rutan mothership.

An alien virus infects the human crew of a refuelling station on Titan, one of the moons of Saturn. The Doctor is also infected and becomes possessed by the will of the Nucleus.

As the Doctor's condition worsens, he instructs Leela to pilot the TARDIS to the Bi-Al Foundation. The only chance of curing the Doctor is to literally get inside his head.

The Doctor and Leela have been cloned and miniaturised and injected into the Doctor's body. There they must fight the virus on a microscopic level before time runs out.

The Nucleus has escaped the Doctor's body and grown to human size. Its plans to spawn and infect the whole galaxy are nearing fruition. And it looks like K-9 has a new master…

The Doctor and Leela arrive in present day England at Fetch Priory where a mysterious skull that is older than mankind is exerting a deadly influence on those around it.

As Thea succumbs to the power of the skull, the Doctor realises that an ancient horror from the mythology of his own people is manifesting at Fetch Priory.

Stahl intends to control the power of the Fendahl for himself. The Doctor and Leela take a trip in the TARDIS to discover the truth about the ancient evil from the dawn of time.

Thea has become the Fendahl Core and Stahl realises that he is out of his depth as his followers transform into the hideous, snake-like Fendahleen.

The TARDIS arrives on Pluto which has been made habitable and turned into a giant factory where the ruthless Company exploits its under-paid workers.

The Doctor is taken prisoner by the Gatherer and sent to the Correction Centre. Leela mounts a rescue attempt, but the Gatherer’s men are waiting.

The Doctor is free but Leela has been captured by the Gatherer and is sentenced to a grisly death by public steaming.

The Others launch a full-scale uprising against the Gatherer and his Inner Retinue while the Doctor confronts the real head of the Company.

The TARDIS lands on a spaceship which is crewed by the survivors of the planet Minyos who are on a quest to find the lost ship, the P7E. Their journey has taken them 100,000 years.

When their ship crashes beneath the surface of a newly formed planet, the Minyan survivors discover what they have been searching for. But their arrival is not welcomed.

The Doctor and Leela attempt to penetrate the Citadel of the Seers to rescue Idas’s father who has been sentenced to death.

The Minyans are eager to recover the race banks that they have waited so long to find, but the Doctor becomes suspicious when the Oracle simply allows Jackson to take them.

Leela is concerned by the Doctor’s strange behaviour when, after a secret meeting with aliens, he returns to Gallifrey and abruptly stakes his claim on the Time Lord presidency.

The Doctor is made president of the Time Lords and immediately orders K9 to lower the planet’s defences and has Leela banished to the wilderness.

The Doctor has betrayed his own people and enabled a Vardan invasion of Gallifrey. Leela joins forces with the Outsiders and prepares to strike back against the aliens.

As the Vardans finally fully materialise on Gallifrey, the Doctor prepares to spring his trap. But does a more deadly alien force lie behind the Vardans?

The Sontarans have taken control of the Capital on Gallifrey and intend to use the power of the Time Lords to rampage through all of time.

Stor, the Sontaran leader, finally gains access to the TARDIS in search of the Great Key of Rassilon and a dangerous game of hide and seek begins inside the Doctor’s ship.

On a mission to collect the six segments of the Key to Time, the Doctor and Romana travel to the planet Ribos where the first segment is protected by the monstrous Shrivenzale.

Garron is attempting to trick the Graff Vynda-K into buying the planet Ribos, but the jethrik that is vital to his plan is really the first segment of the Key to Time.

The Doctor and Romana's search for the first segment of the Key to Time is hampered when the Graff Vynda-K takes them prisoner.

Pursued into the catacombs by the Graff and attacked by the ferocious Shrivenzale, the Doctor and Romana struggle to stay alive and find the first segment of the Key to Time.

In search of the second segment of the Key to Time, the Doctor and Romana travel to the planet Calufrax. But they find that a completely different planet has taken its place.

Still in search of the missing planet, Calufrax, the Doctor and Romana encounter the telepathic Mentiads and Zanak’s ruler, the half man, half robot Captain.

The Doctor has discovered the sinister truth about Zanak and solved the mystery of the missing planet. On the Bridge, the Doctor meets the real ruler of Zanak.

The Doctor and Romana join forces with the Mentiads to prevent the Captain and Xanxia from using Zanak to consume the Earth.

The Doctor and Romana track the third segment of the Key to Time to the vicinity of an ancient stone circle on Earth. But sinister forces are at work and the stones hide a secret.

The leaders of a druidic cult have been killed and it seems that the stones from the stone circle are alive and have a taste for human blood.

As the blood hungry Ogri close in, the Doctor launches a desperate attempt to rescue Romana from hyperspace.

The Doctor releases two alien justice machines from imprisonment who sentenc him to death. Meanwhile Romana urgently searches for clues that will reveal Vivien Fay’s true identity.

Arriving on Tara, Romana locates the fourth segment of the Key to Time with ease, but is captured by the scheming Count Grendel who wants the throne of Tara for himself.

Grendel kidnaps Prince Reynart and seems set to be chosen as Tara’s monarch when Reynart fails to arrive at his coronation. But the Doctor has a plan to scupper the Count’s scheme.

While Romana makes her escape from the castle, the Doctor is lured to a meeting with an android duplicate of her that is programmed to kill him.

The Doctor attempts to gain entry to the castle to prevent the marriage of Romana to Prince Reynart and thwart Grendal’s plans to rule Tara.

Tracing the fifth segment of the Key to Time to the third moon of Delta Magna, the Doctor and Romana are soon caught up in the conflict between humans and the Swampies.

The Doctor arrives in time to save Romana from being sacrificed to the bogus god, Kroll. But it’s not long before the very real Kroll makes its terrifying appearance.

With the giant, squid-like Kroll awake and angry, the Swampies are eager to appease their god by using the Doctor and Romana as sacrificial victims.

With Kroll on the rampage, the Doctor and Romana are appalled to discover that Thawn intends to fire a rocket at the creature which will also kill the Swampies.

Looking for the final segment of the Key to Time, the Doctor and Romana arrive on the planet Atrios which is at war with the neighbouring world of Zeos.

The Marshal demands that the Doctor devise the ultimate deterrent against the attacking Zeons. But the Doctor and Romana begin to suspect that the Marshal is being manipulated.

Journeying to Zeos by transmat, the Doctor finds that it is an empty world. As the Marshal prepares to launch his final attack, the Doctor meets the commander of Zeos’s forces.

With the Marshal poised to fire upon Zeos and the Mentalis computer on a countdown to destruction, the Doctor resorts to desperate measures to prevent a cataclysm.

The Doctor and Romana arrive in the lair of the Shadow, servant of the Black Guardian who also seeks the Key to Time.

The tragic truth of the sixth segment of the Key to Time is revealed and if the Black Guardian can control the Key, the whole of time and space will be plunged into eternal chaos.

The TARDIS lands on the old Dalek homeworld of Skaro where the Doctor and the newly regenerated Romana discover that someone is digging deep beneath the planet’s surface.

Romana is captured and interrogated by the Daleks whilst the Doctor meets the Movellans who are equally interested in discovering exactly what the Daleks are searching for.

Davros has awoken from his centuries long slumber and is taken prisoner by the Doctor before the Daleks can reach him. But the Daleks will stop at nothing to recover their creator.

The Doctor discovers that the Daleks need Davros to break the stalemate in their war with the Movellans, and the Movellans now want the Doctor to fulfil the same purpose for them.

While on holiday in Paris, the Doctor and Romana experience a time distortion. At the Louvre, someone is taking an unusual amount of interest in the Mona Lisa.

The Doctor and Romana become the reluctant guests of Scarlioni who is planning to steal the Mona Lisa despite having six Mona Lisas hidden in his cellar – all of them genuine.

Count Scarlioni is revealed to really be Scaroth, last of the Jagaroth and is funding the construction of a time machine – but for what purpose?

Scaroth intends to travel back in time to save his own people from destruction. But the Doctor can’t allow him to succeed as it would mean the destruction of all life on Earth.

The Doctor and Romana follow a distress signal to the jungle world of Chloris. The planet is ruled by the ruthless Lady Adrasta who takes the Doctor prisoner.

The Doctor has escaped Adrasta’s wrath by jumping down the pit into the last remaining metal mine on Chloris. But the pit is also the home of a monstrous creature.

In the pit, the Doctor establishes contact with the creature and begins to suspect that all is not as it seems.

With Erato now able to communicate, the truth of Adrasta’s scheming is revealed but a terrible retribution has already been put in motion.

A terrible hyperspace accident results in two starships becoming locked together. The Doctor arrives and discovers that the incident may have also released a deadly menace.

The Doctor and Romana are horrified to discover that Tryst has been storing real lifeforms in his CET machine and that someone is smuggling the dangerous narcotic, Vraxoin.

The terrifying Mandrels have escaped from Eden and are attacking everyone aboard the Empress. The Doctor and Romana, accused of being smugglers, are pursued by customs officers.

The Doctor solves the mystery of the drug smuggling racket and the culprits are revealed. But unless the Doctor and Romana act quickly, the villains will escape justice.

With the TARDIS disabled in order to undergo repairs, the Doctor is powerless when Romana is kidnapped by a battleship which is on its way to Skonnos and the formidable Nimon.

On Skonnos, Romana and the Athenian youngsters are forced into the labyrinth of the power complex to meet their fate at the hands of the Nimon.

Trapped inside the power complex, the Doctor and Romana begin to suspect that the Nimon is only the first of a full scale invasion.

On the dying world of Crinoth, Romana discovers the truth behind the Nimon’s empty promises. The Doctor must find a way to shut down the power complex on Skonnos.

The Doctor and Romana visit the Leisure Hive on Argolis. The Argolin, survivors of a war, run the Hive as a tourist attraction but its future is jeopardised by a series of deaths.

The Tachyon Recreation Generator is the cause of the mysterious deaths at the Leisure Hive. Romana makes repairs, and the Doctor becomes a reluctant guinea pig.

The Tachyon Generator has aged the Doctor into a white haired old man, but he discovers the truth behind the machine and uncovers a plot to take control of the Hive.

The obsessed Pangol is determined to give Argolis a future with himself as the leader of the reborn race and plans to strike back at the Foamasi.

On Zolfa-Thura, Meglos plans to steal the ancient and powerful Dodecahedron from the neighbouring world of Tigella. But first, the Doctor must be prevented from interfering.

Masquerading as the Doctor, Meglos penetrates the underground city of Tigella. The Doctor and Romana are trapped in an ever repeating circle of time and powerless to act.

While Meglos escapes with the Dodecahedron, the Doctor is mistakenly held responsible for the theft and is sentenced to a gruesome death as punishment for his crime.

The Doctor must convince the Tigellans of his innocence if he is to prevent Meglos from using the dodecahedron to destroy their world.

The TARDIS enters the universe of E-Space and lands on the planet Alzarius where Mistfall is occurring and creatures are stirring in the swamp.

The Doctor and K-9 are stranded when the TARDIS is stolen by the Marshmen. Romana encounters the Outlers who are regretting their decision not to return to the Starliner.

Romana has been infected by the bite of a marsh spider and the Doctor discovers that the ruling Deciders have been perpetuating a lie to their own people.

The Marshmen are on the rampage through the ship and the Doctor finally uncovers the tragic truth of the Starliner.

The TARDIS lands on a world in E-Space where the primitive inhabitants of a village live in fear of the Three Who Rule.

The Doctor and Romana are taken to the tower and meet the three mysterious rulers. But an ancient evil slumbers beneath their feet.

Adric is taken prisoner by the three vampire rulers. The Doctor discovers that they are facing an unstoppable foe from Time Lord history.

As the Great Vampire begins to awaken from his long sleep, the Doctor formulates a desperate plan to defeat the ancient enemy of his people.

The TARDIS is drawn into an empty white void, somewhere between universes. But they are not the only ones trapped there.

When Rorvik learns that Romana is a time sensitive, he takes her prisoner, forcing her to find a way out of the void. The Doctor attempts to discover what lies beyond the mirror.

As the void begins to shrink around them, Rorvik plans to take desperate measures to escape through the mirror. The Doctor discovers the dark secret of the Tharils’ past.

With the void collapsing around them, time is running out. Rorvik ignores the Doctor’s warnings and takes a desperate gamble which could have fatal consequences.

The Keeper of Traken is nearing the end of his long reign and he requests the Doctor’s help fearing that a terrible evil is about to threaten the peace and harmony of his world.

As Melkur begins to return to life, it manipulates Kassia into doing its bidding. The Doctor and Adric are held responsible for the evil that has come to Traken.

The Keeper nears the end of his life and Melkur is poised to take control of the all powerful source manipulator.

Melkur has become the new Keeper of Traken and begins to access the source manipulator. As the Doctor takes steps to defeat it, he discovers the frightening truth about his enemy.

Deciding to repair the TARDIS’s chameleon circuit, the Doctor goes to Earth to find a real police box. But an old enemy is one step ahead of him.

The Doctor travels to the planet Logopolis in the TARDIS where a series of fateful events are set in motion.

The Master is loose on Logopolis and is determined to learn the planet’s secret, but there is more at stake than he realises.

With the fate of the entire universe hanging in the balance, the Doctor and the Master are forced to collaborate and return to Earth to carry out their plan.