The end. For 16 years, anyways.
After adventuring throughout time and space, Ace finally asks the Doctor to take a visit to her home town — Perivale.note As it turns out, not much is the same since Ace left the town originally and many of her friends have just up and left. The Doctor, however, takes a curious interest in a black cat that seems to be following them around, and while he tries to set a trap for it Ace finds herself poking around a playground when an anthropomorphic cheetah-person riding a horse chases her around the park. Not long after this scene, the Doctor and Ace are whipped away to an exotic alien planet where the Cheetah people come from - and where Ace's friends and a few other extras have been whipped away to. The Doctor is then escorted to the Cheetah people's leader... the Master. And this time, he's acting very darkly. That's what happens when you're allowed to cut loose for the final serial and portray the character as you originally intended without a heaping helping of Camp thrown in to belay complaints that the show is getting too violent for its britches, since, by now, it really doesn't matter, does it?
As it turns out, the planet is some sort of living entity (maybe?) that is slowly infecting the people on the planet with an urge to fight, kill and destroy one another. The Master has already been infected, sporting some neat cat eye contacts, and simply desires to leave the planet. Meanwhile, Ace and her friends are hunted by the Cheetah people and do their best to simply run away. The Doctor and Ace finally meet up again just in time for the Cheetah people to pull an ambush and kill a few of the extras - but not before Midge kills one of the Cheetah people and turns more and more feral.
Separated from the Doctor, Ace meets one of the Cheetah people and kinda befriends her. As it turns out, Ace is also slowly starting to fall to the spell of the planet and is now also sporting those neat contacts. Meanwhile, the Master uses Midge to escape from the planet back to Perivale. The Doctor also uses Ace, after warning her of possible consequences that don't apply to her as she's a main character, to get everyone back home. Waiting for them is the Master, who has taken the time between the two groups arriving to harness the power of a male youth group to challenge the Doctor to motorcycle-jousting.
Either way, the Doctor and the dreaded feral Midge drive at one another and randomly blow up their bikes. The Doctor survives without a scratch while Midge suffers a Critical Existence Failure and dies. Suddenly, the youth group advances on Ace, until that Cheetah person from earlier shows up and tries to chase off the Master. By hugging him. Of course, the Master kills her and meanders off to go steal the TARDIS. There, he encounters the Doctor - and then drags the Doctor back to the now-collapsing-for-some-reason planet where they fight it out in hand-to-hand combat. The Doctor himself sports those adjusted eyes until he realizes that the fighting is killing the planet and that the only way to win is to not fight. The Doctor is whisked away back to Earth and the Master is supposedly left for dead.
Ace mourns the loss of her newfound friend, while the Doctor comes up behind her. Ace takes a few moments to collect herself before saying it's time they go home - back to the TARDIS. The Doctor gives a wonderful monologue as they walk off into the distance, and Ace and the Doctor then go on to have many more adventures... but sadly, for the viewers, this would be the end, after twenty-six years and 155 complete stories...
The Master makes one last appearance, and this time Anthony Ainley was finally allowed to play the character in a more understated way. Ace is also extremely well developed for an old-series companion, culminating the final part of her three part story arc.
According to the writing team at the time, they were putting together scripts for a 'Season 27' when the axe fell. This season would have seen Ace's departure (to study to become a Time Lord at Prydon Academy on Gallifrey) and the introduction of a new companion, a high-class safecracker. Following Big Finish's adaptations of the 'lost' 1986 season, in 2011 they adapted the stories from 'Season 27'.
Doctor Who was pulled off the air following this episode and would not officially return until the 1996 movie (A Children in Need special aired some time during its "rest" from the air, but this is non-canonical). Unfortunately, Ace's adventures with the Doctor up to her eventual departure, plus the full extent of the Seventh Doctor's darkened personality are not depicted, leaving the viewer to scratch their head or make a dash for the Seventh Doctor novels that fill in the holes.
- Actual Pacifist: A very rare Who story to endorse absolute pacifism, as opposed to the usual Martial or Technical kinds.
- An Aesop: This story skewers the "kill or be killed" ethos of the 80's, as personified by Sgt. Paterson and the Master. The Doctor retorts by reminding them both of the Prisoner's Dilemma.
- Alien Sky: The unnamed alien planet has a pink sky.
- And the Adventure Continues: The story — and the original run of Doctor Who — ends with the Doctor and Ace happily walking back to the TARDIS to continue their adventures, with a monologue from the Doctor (written at the last minute, when it was learnt that this would be the final episode indefinitely) to reinforce this.
- And Then John Was a Zombie
- Arc Words: "Good hunting."
- Arch-Enemy: The Doctor and the Master spend a moment discussing their role as this before the climactic battle, when the Doctor catches the Master trying to break into his TARDIS after believing the Doctor to have been killed:
- Arson, Murder, and Jaywalking: "Somewhere there's danger. Somewhere there's injustice, and somewhere else the tea is getting cold."
- Ascended Fridge Horror: While it would not be fully explored until the new series, the concept of what happens to a companion's life when they leave it behind is brought up briefly; when Ace returns home she has been placed on the missing persons list and believed to be dead.
- Attention Deficit... Ooh, Shiny!: Invoked. And justified - they're cats.
- BBC Quarry: Appropriate lighting and decent use of scenery makes this a lot more subtle. Sylvester McCoy actually called this a 5-star quarry at one point.
- With "An Unearthly Child"—the series' first story and final story both feature characters abducted from contemporary suburbia to a brutally primitive environment.
- This serial and "Rose" also form this for the wilderness years of Doctor Who as a whole (if we count the TV movie as part of the wilderness as a whole). Both serials involve the Doctor and his companion, a council estate girl, investigating aliens that are infiltrating contemporary London and assorted mysterious goings-on surrounding them, all of which involve an old enemy of the Doctor.
- Another one: in "An Unearthly Child" the Doctor attempts to bash a caveman's head in, only to be stopped by Ian. At the end of this serial, the Doctor is about to bash the Master's head in, but is stopped by himself.
- The Cameo: British comedic duo Hale and Pace show up as shopkeepers.
- Cat Folk: Played surprisingly straight with the Cheetah people in that they're more Cheetah than man, though the original intention was just the opposite.
- Cats Are Mean: The Doctor faces his final and greatest foe yet: Cheetah yuppies from outer space.
- Caught in a Snare: Ace and her gang set a snare to catch one of the Cheetah people. Unfortunately, the next people to pass that way are the Doctor and Sergeant Patterson.
- Circling Monologue: The part-cheetah Master stalks around the Doctor.
- Crazy Survivalist & Drill Sergeant Nasty: "Sargent" Paterson, the overzealous neighborhood watchman. His American equivalent would be the Guardian Angel vigilantes.
- Creepy Child: Squeak
- Death of a Child: The Doctor pursues the predatory Cheetah People to Earth. The first person he meets is a little girl in tears because someone has killed her cat.
- Disney Death: The Doctor has a head on collision on a motorbike with the enemy, resulting in a huge explosion which we see nobody escape from. Ace begins to mourn his death after she finds his hat and his umbrella laying on the ground. We soon after find out he's somehow just ended up face first in a pile of rubbish with his backside in the air.
- Don't Explain the Joke: A shopkeeper fails to understand the joke his friend is telling him, about two friends confronted by a lion, and the Doctor explains:He doesn't have to outrun the lion, only his friend. Then the lion catches up with his friend and eats him. The strong survive, the weak are killed — the law of the jungle! Yes, very clever, if you don't mind losing your friend. But what happens when the next lion turns up?
- Dying as Yourself: As she dies, Karra reverts to her human form and has time for a final word with Ace.
- Empathic Environment: the violence of the Cheetah people is literally causing their world to break apart.
- Evil Is Petty: The Master apparently goes out of his way to kill the cat of a child he never met before.
- Fang Thpeak: The Master with his new fangs as result of the Cheetah Virus.
- Faux Affably Evil: The Master here is much less the cackling madman viewers had come to expect. In previous stories, Ainley had been told to amp up the ham by production staff, but here was finally allowed to give a much more restrained, brooding and ultimately rather vicious portrayal.
- Fisher Kingdom: Cheetah World
- For the Evulz: The Master's motivation in this episode, apart from saving his own skin from the Cheetah Planet.
- Gadget Watches: The Doctor has a fob watch, which he uses to discover the safest nearby part of the planet.
- Grand Finale: To the Doctor vs the Master story arc for the Original Series. Also, the finale for the classic series and almost the entire mythos as a whole, had the fans not kept the enthusiasm going into the nineties.
- He Who Fights Monsters: Literally, in this case.
- Hellish Pupils: The first stage of Cheetah infection. The Master has it permanently here, and various other characters get brief flashes.
- Homoerotic Subtext: The script and performances are intended to suggest a lesbian subtext developing between Ace and Karra, one of the Cheetah People. One of the reasons that the writer disapproved of the eventual costumes for the Cheetah People was that this was obscured, although many fans still caught on.
- Infant Immortality: Hinted at but ultimately played straight; the Master, through the black cat that summons the Cheetah People, considers kidnapping a group of small children playing in a park to participate in the hunt, but ultimately rejects them as not providing enough sport.
- Sgt. Patterson, the bullying Territorial Army self-defence instructor who proudly lectures a 'survival of the fittest' philosophy, suffers a complete breakdown when actually transported into an environment where he has to put this philosophy into practice. He spends most of the story as a cowering wreck.
- As SF Debris pointed out, it is ironic that the last story to be broadcast before the series was cancelled was called "Survival".
- Killed Off for Real: The Master, again. This time it was supposed to be for really real, but First Law of Resurrection + Joker Immunity = Like You Would Really Do It.
- Milking the Giant Cow: Overacting? On Doctor Who? Never!Doctor: IF WE FIGHT LIKE ANIMALS, WE'LL DIIIIIIIE LIKE ANIMAAAAAAAAALS!
- And that doesn't even begin to do justice to the outtakes. Legend has it that Sylvester McCoy is still the only actor in England to eat an entire BBC Quarry.
- No-Holds-Barred Beatdown: For the Doctor's final fight with the Master in Classic Who.
- Nothing Exciting Ever Happens Here: Perivale.
- One-Word Title
- Pressure Point: The Doctor briefly paralyzes the Sergeant by poking him in the forehead.
- Rearing Horse
- Sexy Cat Person: Not as much as the writer originally envisaged, but Ace's interactions with the Cheetah People are heavily played as a sexual awakening.
- The Social Darwinist: Deconstructing this trope and the "survival of the fittest" ethos of Social Darwinism is essentially the primary theme of this episode.
- Stock Episode Titles: 55 uses.
- Supernatural Gold Eyes: People under the malign influence of the Cheetah Planet acquired golden, cat-like eyes. This included the Master and Ace.
- Trash Landing: After his game of chicken with Midge, the Doctor lands on an old sofa.
- Wrap It Up: By the time the final episode was about to air, it was clear that it was going to be the last for at least a while; the closing monologue was recorded and dubbed in at the last minute to ensure the series ended on an appropriate note.
- You Can't Go Home Again: While Ace visits her hometown in this story, it's not the same as she left it. And after giving into her cheetah transformation enough to bring her friends/prey back to Earth she determines that the Tardis is her home now - a sentiment she restates at the end.