The Doctor brings Ace home to Perivale in West London. A mysterious black cat is wandering around. Humans are disappearing into another dimension, including many of Ace’s old friends. The cat is being controlled by a force in another dimension and choosing who will disappear. An unhappy young man named Stuart (Sean Oliver) is next, followed by Ace herself. She is hunted down by a cheetah on horseback. Then a fitness instructor named Paterson (Julian Holloway) and the Doctor are taken to a planet with a blood-red sky, where he meets his great enemy the Master (Anthony Ainley).
The renegade Time-Lord is not doing well. His eyes and mouth are becoming feline, and he is using a black cat, called a Kitling, to hunt humans from Earth. The planet, he says, is alive and is bewitching people. The indigenous species bred the Kitlings, but they regressed to animals and their civilisation fell. He wants the Doctor to help him escape. Ace has found some of her friends. Shreela (Sakuntala Ramanee) and Midge (Will Barton) are found hiding in the woods with Stuart. He and an unfortunate milkman are hunted down by a cheetah. Ace and her friends find the Doctor and Paterson. A cheetah pack attacks, and Midge kills one as Ace injures another one called Karra (Lisa Bowerman). She nurses Karra and tends her injuries, but the Doctor is frightened when Ace’s eyes change, and she begins to take on cheetah form. For a while, she abandons the Doctor and goes hunting with Karra, but she returns.
Midge is turning into an animal. The Master uses him to teleport to Earth. The Doctor convinces Ace to help him do the same, along with Paterson, Derek (David John), and Shreela. Back in Perivale, Paterson falls back on his self-defence classes and survivalism. The Doctor and Ace search for Midge and the Master, finding them at the Youth Club, where they have killed Paterson for sport, and Midge as well. Karra arrives, welcomed by Ace, but the Master kills her too. The Master teleports the Doctor back to the Cheetah Planet for a final reckoning, but the Doctor resists the violence and is transported away from the dying world, which begins to break up as the Master watches helplessly. The Doctor returns to the TARDIS and Earth to find that the spell is broken, and Ace is human again. He tells her a bit of cheetah will live in her forever.
Writer Rona Munro was disappointed with the Cheetah People. They had a bit of Cheetah eye-makeup and pigmentation and long canine teeth, but the rest of the transformation was to be the actors’ own facial work. But their faces were covered up with silly cat costumes and all the subtlety was lost. She feared the lesbian subtext to Ace’s and Karra’s relationship was lost too, but the fans picked it up all right. In most of her stories, Ace found a young and attractive companion of her own to hang out with—usually female, sometimes male, and often with a bit of romance. In Dragonfire, it was Mel, but apparently, Ace lost her virginity with intergalactic conman Sabalom Glitch. In the Happiness Patrol it was Susie Q; in the Greatest Show in the Galaxy, Dead Beat; in Battlefield, Yuing; in the Curse of Fenric, Captain Sorin; and in Survival, Karra. It is generally assumed that Ace is bisexual. Sophie Aldred is allergic to cats.
Much of the story was filmed in Perivale. The production closed down in August 1990, having been in operation since 1963. Anthony Ainley was replaced as the Master by Eric Roberts in the 1996 TV movie, but Sylvester McCoy was hired to die and be regenerated into Paul McGann. Sylvester McCoy, Anthony Ainley, and Sophie Aldred were all born on August 20. The cheetahs riding horses reminds me of Planet of the Apes, and the story owes a lot to Val Lewton’s Cat People. The production was thought to be a fine ending for the series—deadly serious but with flashes of dark humour, and both McCoy and Ainley were praised. The Doctor came off as a bit Machiavellian, and Ainley was restrained, finally playing the Master as he wanted to, without the over-the-top villainy. Script editor Andrew Cartmel wrote the poetic, melancholic final monologue for the last Doctor Who episode of the Classic Era, which was recorded on its precise 26th anniversary.