With the thirteenth season of Doctor Who, the show began to explore a more “gothic horror” atmosphere, and also sought a balance between UNIT stories and outer-space adventure. Though Sarah Jane remained throughout, Harry Sullivan drifted away from the Doctor, appearing in only two non-consecutive stories. New facts about Time Lord history were revealed, in a story which also introduced an intriguing mystery about the Doctor’s past.
From “Terror of the Zygons”
Brigadier Lethbridge-Stewart uses a device the Doctor calls a psionic beam to summon the TARDIS to Scotland, where UNIT is investigating the mysterious destruction of several off-shore oil rigs, so that the Doctor, Sarah Jane Smith, and Harry Sullivan can assist. They discover it is the handiwork of alien Zygons, trying to make Earth their new home after their own planet was destroyed by a solar explosion. The Doctor discovers the Loch Ness Monster is a cyborg creature under the Zygons’ control. Once all the Zygons have been killed, the Doctor and Sarah Jane leave in the TARDIS, intending to go to London. Harry, however, elects to remain behind with the Brigadier. It would seem the rest of the Zygon diaspora would continue en route to Earth, a journey of several hundred years.
From “Planet of Evil”
Rather than London, the TARDIS materializes in outer space some 30,000 years in the future. Picking up a distress call, it materializes on planet Zeta Minor, which the Doctor and Sarah Jane discover holds an interface between our universe and the antithetical anti-matter universe. The balance of the interface has been upset by a mineralogical expedition, but the Doctor is able to restore the balance and avert catastrophe.
From “Pyramids of Mars”
The Doctor and Sarah Jane converse within the TARDIS.
Sarah Jane: Hey, Doctor! Doctor, look what I found!
The Doctor: Hello, Vicki.
Sarah Jane: What?
The Doctor: Where did you get that dress?
Sarah Jane: I just told you, I found it back there in the wardrobe. Why, don’t you like it?
The Doctor: Yes. Yes, I always did. Victoria wore it. She travelled with me for a time.
Sarah Jane: Well, as long as Albert didn’t wear it. Oh, come on, Doctor. That’s worth a smile, surely. What’s the matter? You should be glad to be going home!
The Doctor: The Earth isn’t my home, Sarah. I’m a Time Lord.
Sarah Jane: Oh, I know you’re a Time Lord.
The Doctor: You don’t understand the implications. I’m not a human being. I walk in eternity.
Sarah Jane: What’s that supposed to mean?
The Doctor: It means I’ve lived for something like 750 years...
Sarah Jane: Well, you’ll soon be middle-aged.
The Doctor: Yes! It’s about time I found something better to do than run round after the Brigadier.
Sarah Jane: Oh, come on, if you’re tired of being UNIT’s scientific advisor, you can always resign!
The TARDIS suddenly lurches as the relative continuum stabilizer fails. They materialize on the site of UNIT headquarters, but seven decades too early. In 1911, it is the house of an Egyptologist, and they discover menacing mummies wandering the grounds. They also detect a radio signal emanating from the planet Mars. The Egyptologist has fallen under the influence of Sutekh, a member of the alien Osiran race, who were worshipped as gods by the ancient Egyptians. Sutekh plans to escape entombment on Earth by destroying the pyramid of Horus, his brother and enemy, located on Mars. The Doctor barely manages to stop Sutekh in time, causing the mansion to burn to the ground in the process.
From “The Android Invasion”
When the TARDIS materializes in a field, the Doctor believes they are on Earth, since oak trees don’t grow anywhere else in the galaxy, but he mentions the TARDIS is way overdue for its 500-year servicing. Witnessing a UNIT soldier walk over a cliff leads the Doctor and Sarah Jane to find a large pod. Though it looks familiar to the Doctor, he curses his memory for getting terrible, saying 300 years ago, he’d have recognized it like a shot. They come upon a deserted English village which is actually a mock-up used to plan a Kraal invasion of Earth. The Doctor gives Sarah Jane the TARDIS key before they split up. Back at the ship, she puts the key in the lock, but is distracted. The empty TARDIS dematerializes. Later, at the site with an android Sarah Jane, the Doctor realizes what happened.
The Doctor: You haven’t lost it. You never had it. Sarah came here, turned the key in the lock and cancelled the pause-control. The TARDIS continued on its set co-ordinates back to Earth.
The Doctor and Sarah Jane stow away on the Kraal’s rocket ship back to Earth and then join the androids in the advance party. However, they each have an android duplicate as well. The Doctor manages to jam the androids’ circuits and foil the invasion plot. Apparently tiring of his role as UNIT’s scientific advisor, the Doctor leaves again without even waiting for the Brigadier to return from Geneva, but presumably he said good-bye to Sergeant Benton and Harry Sullivan.
From “The Brain of Morbius”
The Doctor is furious when the TARDIS is commandeered by the Time Lords and brought to the planet Karn, where lives a secret sisterhood who tend a flame that produces a life-extending elixir. However, the flame seems to be dying.
Maren: The secret of the life elixir is known only to our Sisterhood and the High Council of the Time Lords. Since the time of the stones, we have shared the elixir with them. But now there is none to share. The few vials that are left I have kept for ourselves. But for months I have felt that the Time Lords would come to rob us of these last precious drops.
The Doctor and Sarah Jane stumble upon the laboratory of mad scientist Mehendri Solon, an earthman from the future whom the Doctor knows by his academic reputation, who is trying to engineer a new body for Morbius, a war criminal banished from Gallifrey. Solon decides he must have the Doctor’s head for his creature, but the unconscious Doctor is spirited away by the mystical power of the Sisterhood of Karn, who believe he has been sent to steal the elixir.
Ohica: Morbius was executed for leading the rebellion. His body was placed in a dispersal chamber and atomised to the nine corners of the universe.
The Doctor: I know that. But I tell you, Maren, just for a second, before I passed out, his mind touched mine. I felt his burning hatred and anguish. Morbius is alive!
Maren: I suppose you think raising these old fears can somehow help you, but I was present at his execution! Morbius is dead, Doctor, and you will join him very shortly!
Somehow, Morbius and Solon were able to outwit the Time Lords, and Morbius’ brain was removed from his body before his atomization. Solon then connected the brain up to a life-support system through which Morbius could still communicate while he worked to create a new body for brain-transplantation. Solon makes a deal with the Sisterhood to deliver the escaped Doctor in exchange for his head. However, when Morbius learns that the Doctor is a Time Lord, he refuses to wait and demands Solon put the brain into an artificial head attached to a patchwork body, but the desperate measures drive Morbius to the brink of total madness. The Doctor challenges Morbius to a mind-bending contest, a sort of telepathic wrestling match. A psychic image appears between them of the Doctor, pushed back through his regenerations by the mental power of Morbius. Strangely, beyond the Doctor’s first persona is a succession of other, unfamiliar faces. Morbius shouts, “How far, Doctor? How long have you lived? Back, back to your beginning!” The Doctor collapses and Morbius leaves the laboratory, only to be driven over a cliff by the Sisterhood. Maren then sacrifices herself to provide the Doctor with enough elixir to survive. The Doctor leaves the Sisterhood, now under Ohica’s leadership, with the means to keep the fire burning brightly.
Morbius was apparently once the leader of the High Council of the Time Lords, but became a ruthless tyrant with a band of fanatical followers. He formed a personal army of “riffraff and mercenaries, the scum of the universe” and laid waste to several planets. When he wiped out the civilization on Karn in an attempt to gain control over the Elixir of Life, however, the Time Lords came to the aid of their ancient allies, the mystical Sisterhood. Maren believes the Time Lords acted only out of self-interest. Morbius was sentenced to be executed, but he hatched a plan with the earthman Solon, living on Karn at the time of his trial, to escape death. The secret of the elixir revealed, the Sisterhood went into hiding and destroyed any passing spacecraft, turning Karn into a spaceship graveyard. The Doctor tells Maren that the Time Lords use the elixir only in times of acute regenerative crisis, so as not to fall into the trap of immortality, and he extracts from them a promise not to down any more passing ships.
From “The Seeds of Doom”
When a scientific expedition unearths a strange plant pod deep in the Antarctic ice, the Doctor is once again called in as UNIT’s scientific advisor. He and Sarah Jane travel to the bottom of the world, where the Doctor doesn’t bother to bundle up any more than usual, even while outside at night. The Doctor realizes an alien Krynoid, a sort of interstellar man-eating vegetable, is trying to overrun the Earth. The pod is brought back to England by a mad plant fancier, but with the help of UNIT’s arsenal, the Doctor is able to blow the giant intelligent weed to smithereens. The Doctor decides that he and Sarah Jane should take a holiday to Cassiopeia.