[[quoteright:350:http://static.tvtropes.org/pmwiki/pub/images/survival.jpg]]
[[caption-width-right:350:"Doctor, look! [[FurryFandom Furries!]]"[[note]]No folks, in all seriousness, we'll miss the Classic Era.[[/note]]]]
->''"There are worlds out there where the sky is burning, and the sea's asleep, and the rivers dream. People made of smoke, and cities made of song. Somewhere there's danger, somewhere there's injustice, and somewhere else the tea's getting cold! Come on, Ace, we've got work to do!"''
-->-- The final monologue from '''the Seventh Doctor''' for this episode.[[note]]It was edited in once they knew the show had been cancelled.[[/note]]

->''"If we fight like animals, we die like animals!"''
-->-- '''The Doctor''''s revelation on how fighting works.

After adventuring throughout time and space, Ace finally asks the Doctor to take a visit to her home town - Perivale. 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 [[CatFolk 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 [[BBCQuarry 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.

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 [[HoYay 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 CriticalExistenceFailure and dies. Randomly, 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... [[ScrewedByTheNetwork but sadly, for the viewers, this would be the end...]]

...anyone in the mood to [[Literature/DoctorWhoNewAdventures read]] some [[Literature/DoctorWhoMissingAdventures books]]? Audios, perhaps?

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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 [[Recap/DoctorWhoS26E2GhostLight three part]] [[Recap/DoctorWhoS26E3TheCurseOfFenric story arc]].

[[WordOfGod 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 Creator/BigFinish's adaptations of the 'lost' 1986 season, in 2011 they adapted the stories from 'Season 27'.

Incidentally, Ace's... special friend (Karra the Cheetah-person) was played by Lisa Bowerman, who would proceed to the Franchise/DoctorWhoExpandedUniverse as the voice of Professor Franchise/BerniceSummerfield.

''Doctor Who'' was pulled off the air following this episode and would not officially return until the 1996 movie (A ''ChildrenInNeed'' 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.

!!Tropes
* ActualPacifist: a very rare Who story to endorse absolute pacifism, as opposed to the usual Martial or Technical kinds.
* AndTheAdventureContinues: The story -- and the original run of ''Series/DoctorWho'' -- 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.
** AdaptationExpansion: ''Several!'' You can go the divergent route of the Virgin New Adventures, which are DarkerAndEdgier and play out the Cartmel Masterplan, or take a look at the Big Finish Audios, which are considered part of the same timeline for the Seventh Doctor as the television series. And if neither of those tickle your fancy, there is "Death Comes to Time", which slams the book on the Seventh Doctor a bit harshly.
* AndThenJohnWasAZombie
* ArcWords: "Good hunting."
* ArchEnemy: 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:
-->'''The Doctor:''' [[ArcWords Good hunting?]]\\
'''The Master:''' Yes... it would have been too easy. It seems we must always meet again...\\
'''The Doctor:''' They do say OppositesAttract.
* BBCQuarry: 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.
* BookEnds:
** 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.
* CatFolk: Played surprisingly straight with the Cheetah people in that they're more Cheetah than human.
** Though the original intention was something much more human.
* CatsAreMean
* CaughtInASnare: 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.
* CreepyChild: Squeak
* DisneyDeath: The Doctor.
* DistractedByTheShiny: Invoked. And justified - they're ''cats''.
* DyingAsYourself: As she dies, Karra reverts to her human form and has time for a final word with Ace.
* EmpathicEnvironment: the violence of the Cheetah people is literally causing their world to break apart.
* EvilIsPetty: The Master apparently goes out of his way to kill the cat of a child he never met before
* FauxAffablyEvil: The Master here is much less the cackling madman viewers had come to expect. In previous stories, Ainley had been told to [[LargeHam amp up the ham]] by production staff, but here was finally allowed to give a much more restrained, brooding and ultimately rather vicious portrayal.
* FisherKingdom: Cheetah World
* ForTheEvulz: The Master's motivation in this episode, apart from saving his own skin from the Cheetah Planet.
* FoxHunting: [[DiscussedTrope Discussed]]; the Doctor and Ace meet Ange, who's collecting for a group of hunt saboteurs. Rather than contribute, the Doctor takes the opportunity to contrast the 'noise and pantomime' of foxhunting with the stealthy predator he's beginning to suspect is preying on the local population.
* GadgetWatches: The Doctor has a fobwatch, which he uses to discover the safest nearby part of the planet.
* GrandFinale: 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.
* HeWhoFightsMonsters: Literally, in this case.
* HellishPupils: The first stage of Cheetah infection. The Master has it permanently here, and various other characters get brief flashes.
* HomoeroticSubtext: 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.
* InfantImmortality: 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.
* {{Irony}}: 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.
* KilledOffForReal: The Master, again. This time it was supposed to be for really real, but FirstLawOfResurrection + JokerImmunity = LikeYouWouldReallyDoIt.
* NoHoldsBarredBeatdown: For the Doctor's final fight with the Master in Classic Who
* NothingExcitingEverHappensHere: Perivale
* OneWordTitle
* PressurePoint: The Doctor briefly paralyzes the Sergeant by poking him in the forehead.
* RearingHorse
* TheCameo: Comedic duo Hale and Pace show up as shopkeepers.
* TheSocialDarwinist: Deconstructing this trope and the "survival of the fittest" ethos of Social Darwinism is essentially the primary theme of this episode.
* StockEpisodeTitles: 55 uses
* TrashLanding: After his game of chicken with Midge, the Doctor lands on an old sofa.
* WrapItUp: 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.
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