The twenty-sixth season of Doctor Who would end up being the last of the original series, though there was no grand finale. However, the character of Ace was explored in unusual depth over the course of the season, which began with a new UNIT story featuring the return of Brigadier Lethbridge-Stewart. Finally, the Master reappeared for one more showdown with the Doctor. The next televised adventure would be the problematic 1996 TV movie, followed at last by the new series beginning in 2005.
Aboard the TARDIS, the Doctor picks up a mysterious signal, a pan-dimensional call for “Merlin.” Locked into the source of the signal, the TARDIS materializes on the shore of Lake Vortigern in Carbury, England at a time the Doctor describes to Ace as “a few years in your future.” Near an archaeological dig, they find a UNIT operation underway, now under the command of Brigadier Winifred Bambera. When word of the Doctor’s presence makes its way to Geneva, Brigadier Alistair Gordon Lethbridge-Stewart is called out of retirement. A cadre of Arthurian knights appear from another dimension, and the Doctor and Ace encounter one in a barn, who recognizes the Doctor as being Merlin, to the Doctors bewilderment.
Ace: You’ve got it wrong, mate. This is the Doctor.
Ancelyn: Oh, he has many names, but in my reckoning, he is Merlin.
The Doctor: You recognise my face, then?
Ancelyn: No, not your aspect. It is your manner that betrays you. Do you not ride the ship of time? Does it not deceive the senses, being larger within than without? Merlin, cease these games and tell me truly, is this the time?
Ancelyn has come to retrieve the sword Excalibur, hidden within a spacecraft at the bottom of the lake. He is pursued by the sorceress Morgaine and her army, and she has summoned a demonic creature called the Destroyer, which Brigadier Lethbridge-Stewart disintegrates by shooting silver bullets into it. Morgaine then hijacks the nuclear missile which UNIT was transporting, but the Doctor is able to convince her that nuclear war is inherently dishonorable. She and her son Mordred are taken into custody.
It would seem that at some point in his own future, the Doctor will travel to a parallel universe where the Arthurian legends are all true, and he will be mistaken for Merlin the Magician. The Doctor will assist King Arthur and his knights in an apocalyptic battle with Morgaine and her forces of evil. Unbeknownst to Morgaine, Arthur will be slain in the battle, and the Doctor will place his remains along with Excalibur aboard a spacecraft and move it sideways in time to the eighth-century Earth of his home universe. He will then construct a tunnel to the surface of the lake, and leave a note for his past self to find inside Arthur’s helmet. The Doctor will then apparently be sealed in some ice caves with no hope of escape, but not before starting the myth that Arthur will one day return for a reckoning.
From “Ghost Light”
Ace tells the Doctor of a traumatic event from her childhood: in 1983, when she was 13 years old, her best friend’s house in Perivale was firebombed, probably by white supremacist skinheads. In a rage, Ace broke into a “haunted house” called Gabriel Chase, and, terrified by a sense of powerful evil of an alien nature, she burned the house to the ground. Wanting to learn the nature of this evil presence, the Doctor takes them back to Gabriel Chase in 1883, where they meet a cast of bizarre characters, mutated by a powerful alien creature called Light, who once catalogued all life on Earth and then becomes distraught when he discovers that his research has been made obsolete by evolution. Gabriel Chase had been built on top of Light’s spacecraft, and his evil presence lingers long after he and his ship are gone.
From “The Curse of Fenric”
The TARDIS materializes at a military installation for codebreaking on the British coast during World War II, but the base personnel have become obsessed with an ancient Viking curse. Ace meets Kathleen Dudman and her baby daughter Audrey, whom she learns are her grandmother and mother, respectively. The Doctor discovers that the base is actually a secret stockpile for chemical weapons. They are attacked by a number of aquatic vampire-like creatures the Doctor calls “Hæmovores,” but he is able to drive them off by emitting a strange, singing sort of noise, which, he claims, creates a psychic barrier against such monsters, which have been created through the evil power of Fenric.
The Doctor: The beginning of all beginnings, two forces only -- Good and Evil. Then, chaos. Time is born, matter, space -- the universe cries out like a newborn. The forces shatter as the universe explodes outwards. Only echoes remain. Yet somehow -- somehow, the Evil force survives. An intelligence -- pure evil!
Ace: That’s Fenric?
The Doctor: No, that’s just Millington’s name for it. It has no name. Trapped inside a flask. The genie in the bottle.
The evil intelligence called Fenric manifests itself using a succession of human bodies as hosts. The Doctor and Fenric have met at some point in the past, and Fenric is back for revenge, an ongoing game of chess used as a metaphor for their conflict.
Fenric: Where is the Time Lord?
Millington: Time lord?
Fenric: For seventeen centuries I was trapped in the shadow dimensions because of him. He pulled bones from the desert sands and carved them into chess pieces. He challenged me to solve his puzzle. I failed. Now I shall see him kneel before me, before I let him die.
Fenric has manipulated events to bring together all those touched by his curse -- the descendants of the Viking raiders who buried the oriental flask in which he was trapped, including Ace, as well as the last survivor of the future Earth, horribly mutated by industrial pollution into the Ancient Hæmovore -- in order to unleash the deadliest of poisons to kill all life on Earth. The Doctor realizes the only way to defeat Fenric is to break the curse, and the only way to do that is to crush Ace’s faith in him.
Fenric: Kneel if you want the girl to live!
The Doctor: Kill her.
Fenric: The Time Lord finally understands!
The Doctor: You think I didn’t know? The chess set in Lady Peinforte’s study? I knew.
Fenric: Earlier than that, Time Lord. Before Cybermen. Ever since Iceworld, where you first met the girl!
The Doctor: I knew. I knew she carried the evil inside her. You think I would have chosen a social misfit if I hadn’t known? She couldn’t even pass her chemistry exams at school. And if she manages to create a time storm in her bedroom, I saw your hand in it from the very beginning.
The Doctor: She’s an emotional cripple. I wouldn’t waste my time on her, unless I had to use her somehow.
The curse thus broken, the Ancient Hæmovore is free to act, trapping Fenric inside a testing chamber, where the deadly chemicals destroy them both. With the death of his corporeal host, Fenric is presumably once more banished to the shadow dimensions. The Doctor seems to have brought Ace to this time and place specifically for the showdown with Fenric, and this may explain the mentor relationship he has with her, helping her to face her inner demons and mature from a troubled teen into a well-adjusted young woman, whose real name is most probably Dorothy Dudman.
When Ace mentions that she wonders what her old friends are up to, the Doctor takes her back to contemporary Perivale. Ace learns that several of her friends have since vanished under mysterious circumstances, and then she, too, is kidnapped -- transported to an alien planet inhabited the Cheetah People, who hunt humans for food. The Doctor is then transported there as well, where he soon sees a familiar face -- the Master. Having become stranded on the disintegrating planet, the Master established a mind-link with the kitlings, creatures that look like black cats that possess the power of teleportation, and had them bring the Doctor there as well, the Master believing that his old adversary would surely find a means of escape.
The Doctor: Why should I help you?
The Master: It’s not just death that we’re all facing. This place bewitches you. If we stay here, we’ll be like the people who built these. They thought they could control the planet -- the wilderness. They were the ones who bred the kitlings -- creatures with minds they could talk to, eyes they could see through, the way I do. It only led to their corruption. We shall become like them. We shall become animals!
Like the Master, Ace also is affected by the power of the planet and begins to mutate into a more feline form, a process she finds seductive. As the mutation progresses, the power of teleportation arises as well, and the Master uses one of Ace’s mutated friends to get to Earth, where he tries to suppress his own transformation.
The Master: You are all animal now. You’re so weak, your will devoured. A stronger mind will hold onto itself longer. A will as strong as mine -- how much longer? If I have to suffer this contamination, this humiliation, if I am to become an animal, then like an animal I will destroy you, Doctor. I will hunt you, trap you, and destroy you!
Ace likewise transports the Doctor and her other friends back to the TARDIS, though the Doctor fears it may make her transformation irreversible. She is then able to track the Master’s movements. She and the Doctor become separated, and the Doctor finds the Master apparently trying to break into the TARDIS.
The Doctor: Good hunting?
The Master: Yes. It would be too easy. It seems we must always meet again.
The Doctor: They do say opposites attract.
The Master: But this is the end, Doctor. You see it? It’s a power -- the power from that planet. It’s growing within me. Are you frightened yet?
The Doctor: No.
The Master: You should be. You should be. It nearly beat me. Such a simple, brutal power, just the power of tooth and claw. It nearly destroyed me, a Time Lord. But I won. I controlled that force, Doctor. And now, at last, I have the power to destroy you! Welcome to my new home, Doctor!
The Doctor: They’re gone! What are we doing? I’ve got to stop! We’ve got to go home!
The Master: Can’t go! Not this time!
The Doctor: Yes, we can!
The Master: Escape to what? I don’t choose to live as an animal!
The Doctor: If we fight, we’ll destroy this planet! We’ll destroy ourselves!
The Master: You should have killed me, Doctor!
The Doctor: if we fight like animals, we die like animals!
After being abandoned by the Cheetah People, the planet finally disintegrates as the Doctor is suddenly teleported back to Perivale and the TARDIS and the Master, presumably, to parts unknown. He catches up to Ace, mourning the death of the Cheetah Woman she had befriended, who was killed by the Master. Her body is then taken by another Cheetah Person and teleported away.
Ace: Where have they gone?
The Doctor: They’ve been taken back to the wilderness. The place is different, but the hunt goes on. You know all about the hunt, don’t you, Ace?
Ace: I felt like I could run forever, like I could smell the wind and feel the grass under my feet and just run forever!
The Doctor: The planet’s gone, but it lives on inside you. It always will.
The Doctor and Ace return to the TARDIS to continue their travels.
Jump Back: A Brief History of Gallifrey
Jump Back: A Brief History of the Master