[[quoteright:350:http://static.tvtropes.org/pmwiki/pub/images/dark_colin_3851.jpg]]
[[caption-width-right:350: The Doctor gazes into the abyss, and the audience gazes back. [[OverlyLongGag At least we can't see his coat...]] (I think we're done with the coat jokes... for now.)]]
->''"In all my travels through time and space I have battled against evil, against power-mad conspirators. I should have stayed here! The oldest civilization: decadent, degenerate and rotten to the core! Power mad conspirators? Daleks, Sontarans, Cybermen they're still in the nursery compared to us! Ten million years of absolute power: that's what it takes to be '''really''' corrupt!"''
-->--'''The Doctor''', finally fed up with the KangarooCourt he's been thrown into, ripping into his own people's despicable acts with a lovely monologue.

->''"Carrot juice, carrot juice, carrot juice..."''
-->--The final line of the adventure; sadly, Colin Baker's final line as '''the Doctor'''. (Well, at least on TV...)

The one where Colin gets fired.

Picking right up where the previous story left off, ''The Ultimate Foe'' opens up with the Doctor being accused of genocide. The Doctor objects, and both he and the Valeyard get into a well-written argument that suddenly ends when [[Recap/DoctorWhoS23E1TheMysteriousPlanet Sabalom Glitz]] and future companion Melanie show up almost literally out of nowhere. When the Doctor asks how they got there, the Master shows up to torment the Doctor and everyone else - revealing major plot points like how Ravalox (from the first part) was really the Earth. Furthering his gloating, the Master reveals that [[WhamLine the Valeyard is really the Doctor]].

Well, not exactly. The Valeyard is a piece of the Doctor: specifically, the Doctor's dark side, split off from around the last of his regenerations. Even when being specific, this origin is incredibly abstract.

Either way, the Valeyard flees into the Matrix ''([[Film/TheMatrix no, not that one!]] We've been over this!)'' and the Doctor and Glitz pursue. Inside the Matrix, the Doctor and Glitz are tormented by the Valeyard repeatedly until finally winding up in what can only be described as a world that was co-designed by MC Escher and Charles Dickens on PCP and acid. The Valeyard continues to gloat in his own way, while Mel and the entire judge and jury stare at the viewscreen like it's the Monday Night Football game.

Not much later, things go back to the courtroom, where the Doctor is convicted of his so-called crimes and will be executed. Only it's all an illusion, and the Doctor [[ThePlan knows it's an illusion]], but Mel [[GambitPileup doesn't know that he knows]], so she runs into the Matrix to try and stop it all. The Valeyard gets all pissy about this, deciding to vanish for the time being. Meanwhile, Glitz and the Master decide to steal the records of the Matrix to make some cash in a story that, sadly, goes nowhere.

Finally, the Doctor and Mel find themselves face-to-face with the Valeyard, and his plans to destroy the current government of the Time Lords. Through a brief struggle, the Valeyard spits out technobabble about things not going his way and is finally defeated [[NotQuiteDead (OR IS HE...?!)]]. The Time Lords saved, the random Time Lady presiding over the trial tells the Doctor that Peri survived and is living with [[Recap/DoctorWhoS23E2Mindwarp King Yrcanos]] after his rambling that she would be his queen... for [[BuxomIsBetter some reason]]. Mel and the Doctor leave together, presumably for him to drop her off somewhere for his future self to pick up later ''(See the Past Doctor Adventures novel ''Business Unusual''... or maybe the Big Finish Audio'' [[Recap/BigFinishDoctorWho169TheWrongDoctors The Wrong Doctors]].'' Either one works.)'', and the Sixth Doctor [[TheNthDoctor goes on]] to many, many more [[Recap/DoctorWhoS24E1TimeAndTheRani adventures]], where th-

...

[[WhatCouldHaveBeen Oh.]]

...

[[ExecutiveMeddling Shit.]]

...

...

[[Recap/BigFinishDoctorWhoSpecialsRealTime Anybody know the name]] [[AnimatedAdaptation of a good animator?]]
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The two episodes were written by four different people, though few really notice. The first episode was written by Creator/RobertHolmes and script editor Eric Saward together, with Holmes slowly dying from disease. He passed away without finishing the final episode, which was finished off by Eric Saward himself and then withdrawn when Producer Creator/JohnNathanTurner disagreed with it. The final episode was then entrusted to Pip and Jane Baker ''(no relation to Colin '''or''' Creator/TomBaker, who themselves are also unrelated, and none of them are related to prolific 70s Who writer Bob Baker, either)'', who had written [[Recap/DoctorWhoS22E3TheMarkOfTheRani previously]] for [[Recap/DoctorWhoS23E3TerrorOfTheVervoids the series]]. In fact, Pip and Jane weren't even allowed to ''see'' the original script, not to mention they had no clue how the story was supposed to end.
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!!This story provides examples of:
* AllJustADream: The entirety of Season 23 is revealed to have been an inaccurate reconstruction of what really happened. Of particular note, it turns out that Peri's death never really happened and instead she is happily living with King Yrcanos (despite the fact that he seems to be violently insane, though that may just be more Matrix tampering).
* BelatedHappyEnding: Peri, assumed dead after the events of "[[Recap/DoctorWhoS23E2Mindwarp Mindwarp]]," gets one of these.
* {{Bizarrchitecture}} with a SteamPunk flavour.
* CharacterTics: As the Valeyard notes, he still displays some of the Doctor's habits and eccentricities.
* CreepyChildrenSinging: As the Doctor explores the Valeyard's Dickensian private world, Creepy Children sing "Ring-a-Ring-o-Roses" in the background; it isn't clear if he can hear them or not.
* DefectorFromDecadence: The Doctor's experiences in this season kill any shred of respect he still had for Time Lord society. After this, he only misses Gallifrey once there's no going back.
* TheEndOrIsIt: After the Doctor and Mel depart, the Inquisitor starts organizing the surviving Time Lords with the intent of restoring order to Gallifrey. She gives an order to the Keeper of the Matrix, who then turns to the screen to reveal the Valeyard himself. Cue end credits.
* EnemyWithin: The Master's ambiguous wording when describing the Valeyard infers that he's either the Doctor himself, after all his evil took over him in a potential future, or...
* EnemyWithout: The Doctor's evil split from him.
* EvilMeScaresMe: The Doctor's reaction to the Valeyard's true nature is one of abject horror. It's been argued that the Doctor is petrified of him returning in ''any'' form. The ExpandedUniverse went further on this, to the point that an entire incarnation's personality was locked away for a time because of that fear. Hell, even ''the Master'' fears him.
** Technically, also FutureMeScaresMe
* ExactWords: The Master's description of the Valeyard as originating from somewhere between the Doctor's "twelfth" and "final" incarnations was retroactively made into this a long time later (well, either that or the Master was just lying). At the time, it was assumed that the Doctor's thirteenth incarnation would ''be'' his final one, and thus the assumption is clearly that the Valeyard - whatever exactly he is - would be created somehow when the twelfth incarnation of the Doctor regenerated into the thirteenth. [[Recap/DoctorWhoS33E13TheNameOfTheDoctor Later]] [[Recap/DoctorWho2013CSTheTimeOfTheDoctor episodes]] made it so that we've now ''already seen'' more than twelve incarnations of the Doctor, with [[Recap/DoctorWho2017CSTwiceUponATime still more to come]], and no clear idea any more of which number of incarnation (if ''any'') we can expect to be the "final" one. If we assume that the Master was correct, then "between twelfth and final" is now retroactively just a fancy way of saying "some point after Creator/MattSmith but before the BBC finally cancels Series/DoctorWho for good".
* FieryCoverup: The Time Lords are revealed to have engaged in this on a planetary scale, nearly wiping out the Earth and moving it across the galaxy, and then willing to execute the Doctor, who accidentally stumbled across the evidence without even realizing it in order to hide their own embarrassing indiscretions.
* GovernmentConspiracy: Committed by the Time Lord High Council.
* HamToHamCombat: Creator/ColinBaker vs Michael Jayston!
* HijackedByGanon: Subverted - the Master turns out to have caused most of the events of the "Trial" season, but then the Valeyard took advantage of his actions to become the real "Ultimate Foe".
* {{Infodump}}: The first fifteen minutes of episode one are basically one long courtroom infodump courtesy of the Master, who reveals the answers to almost all of the questions that have been building throughout the entire Trial of a Time Lord story arc.
* MeaninglessMeaningfulWords: Perhaps the most famous example from Doctor Who's half-century run: "'''There's nothing you can do to prevent the catharsis of spurious morality!'''"
* MuggedForDisguise: If the final moments are anything to go by, the Valeyard seems to have robbed the Keeper of the Matrix of his robes.
* NotSoAboveItAll: There is a golden moment where the Valeyard in lecturing the Doctor in his typical dour manner, even explicitly stating that he "wishes not to be contaminated by [the Doctor's] whims and idiosyncracies." ...when Glitz tries to participate in the conversation, the Valeyard teleports directly behind him for the explicit purpose of insulting him in a rather comedic way. Then again, his compulsion to out-cool adult male companions and recurring characters was always one of the Doctor's character flaws...
* ObstructiveBureaucrat: Mr. Popplewick inside the Matrix, the Inquisitor outside of it.
* OhCrap: The Doctor's reaction when the Master reveals that the Valeyard is actually the embodiment of the Doctor's dark side, taken from a point after his twelfth incarnation. The look on the Doctor's face shows he knows full well what he's capable of--and this is long before the final events of the Time War.
* TheOnlyOneAllowedToDefeatYou: Stated by the Master in part two as to why he's helping the Doctor.
* PurpleProse: The Valeyard is prone to overly-verbose language, because his dialogue was penned by Pip & Jane Baker.
* TheReasonYouSuckSpeech: After having put up with the KangarooCourt of the previous season and the numerous pompous and self-righteous condemnation of his character from the Time Lords, when he learns that the whole thing was orchestrated as part of a cover-up of a theft of Time Lord secrets that also resulted in the destruction of the Earth the Doctor takes the opportunity to tell the assembled Time Lords exactly what he thinks of them.
** [[AlternateCharacterInterpretation You can also interpret that speech]] as Robert Holmes and Colin Baker himself telling off Creator/TheBBC for their contemptuous treatment of the show and plans to take it off the air.
* SesquipedalianLoquaciousness: In episode two, as is pretty much par for the course in Pip and Jane Baker scripts. Key example: "there's nothing you can do to prevent the catharsis of spurious morality."
* SpannerInTheWorks: TheMaster, of all people, derails the whole plot against the Doctor. Not out of any sense of altruism, naturally, but for both the chance to [[PlayingBothSides pit two aspects of the Doctor against himself]] and topple the High Council of Time Lords.
** For bonus points, he makes himself this as literally as he possibly can, by revealing the plot from within the Time Matrix viewing screen.
* TeleportSpam: The Valeyard.
* VictorianLondon: Part of the story takes place in a simulation of VictorianLondon.
* VillainousRescue: The Master rescues the Doctor when he's on the verge of being gassed by the Valeyard because he considers the Valeyard the bigger threat...although he promptly uses the Doctor as live bait to ambush the Valeyard.
* WhamEpisode: The Valeyard is really a corrupted future incarnation of the Doctor, employed by the Time Lord High Council to destroy the Doctor to prevent him from revealing their role in the attempted genocide of the human race. The Doctor's only ally in this is the Master, who (obviously) cannot be trusted.
* WhamLine:
-->'''The Master''': They made a deal with the Valeyard, or as I've always known him, the Doctor...
* XanatosSpeedChess
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Hey, don't be sad ol' Sawbones Hex got drummed out of the series after only eleven episodes. He was rescued by Big Finish! [[Recap/BigFinishDoctorWho Take some spare time to look at the overwhelming collection of Sixth Doctor audios.]] And if you want to see more of him, start [[Recap/BigFinishDoctorWho001TheSirensOfTime HERE]]. But sadly (or perhaps mercifully is a better word), you can't witness his coat in action as you listen to his stories; while audio can broadcast the dulcet tones of the Sixth Doctor, it doesn't do so hot where the visual department is concerned, let alone visualizing a coat that is a certified cornucopia of clashing colour hues.

And if you ''really'' want to know what happened to the Sixth Doctor, have no fear! [[Recap/BigFinishDoctorWhoSpecialTheLastAdventure Big Finish released an audio series in August 2015 to deal with his regeneration story.]]