[[caption-width-right:350:Get that [[CrosshairAware triangle]] off the screen, pronto! What do you think this is, [[TheIlluminati the Illuminati]]? At this rate, you'll give half the viewers triangle fever, triangle vision, or some other three-sided malady!]]
->''Through the millennia, the Time Lords of Gallifrey led a life of peace and ordered calm, protected against all threats from lesser civilisations by their great power. But this was to change. Suddenly and terribly, the Time Lords faced the most dangerous crisis in their long history...''
-->-- The OpeningNarration, as read by '''The Doctor'''
->''"[[ARareSentence Vaporisation without representation is against the constitution!]]"''
-->-- '''The Doctor''' protests his punishment
This serial is important in that it is the first to take place entirely on Gallifrey. In addition, ''many'' details of Time Lord society are [[WorldBuilding revealed]] for the first time: the 13 regeneration limit, the political system, the chapter houses (Prydonian, Arcalian, etc.), the swanky Time Lord regalia and their giant hats, the Sash and Key of Rassilon, the Eye of Harmony, and the Matrix. The story also introduced the Doctor's mentor Borusa and, perhaps most notably, mentioned Rassilon for the first time. Bernard Horsfall (last seen as the Time Lord who sentenced the Doctor to exile in "[[Recap/DoctorWhoS6E7TheWarGames The War Games]]") returns as Chancellor Goth, and although the casting wasn't entirely deliberate, there's nothing to indicate that it's not simply the same character. And finally, the Master returns, played by Peter Pratt. Judging from the Master's atrocious complexion, he's seen far better days since the last time he appeared.
This story is also known for having no companions. Ultimately, this proved the companion's use as TheWatson, as it was hard to convey the Doctor's thoughts without someone for him to explain them to. The post-2005 stories with no regular companions tend to have a guest character filling the role temporarily.
Summoned to Gallifrey and with no companion at his side, the Doctor gets a surprise FlashForward when he sees himself assassinating the Lord President. He tries to stop it from happening, but he can't prevent the assassination and is promptly arrested by Chancellor Goth.
However, it becomes apparent that this is a plot of the Master's -- having used up all his regenerations, the Doctor's EvilCounterpart managed to get into some kind of offscreen accident and can't regenerate into a new body any longer. He's reduced to a skeletal husk, his skin rotting off and causing him constant agony, and now he wants to get his hands on the Key and Sash of Rassilon: the Presidential regalia.
The Doctor escapes execution by virtue of LoopholeAbuse (to everyone's annoyance) and becomes a Presidential candidate, granting him immunity for a few days. The only other candidate is Chancellor Goth. The Doctor convinces a few sympathetic Time Lords to hook his brain up to the virtual reality of The Matrix (no, not [[Film/TheMatrix that one]]). The Matrix is a knowledge database, which is made up of the VirtualGhost brainwaves of dead Time Lords.
Inside the virtual reality of the Matrix, the Doctor fights a hallucinatory masked opponent who hunts him down with trains, planes, hypodermic needles, guns and poison. He loses about half his wardrobe in the process and gets all dirty and bloody, and when the mysterious hunter is revealed to be Chancellor Goth, the two end up mud-wrestling in a pond and ripping each other's clothing off. With that out of the way and Goth finally dead, the Doctor is brought back to reality, but the Master already has the regalia.
The Master begins opening the legendary Eye of Harmony, the core of a black hole, which was discovered by Rassilon during the foundation of Time Lord society. He's stopped by the Doctor and falls into a fissure. The Time Lords elect the Doctor as the new President, but he slips away and absconds, followed shortly afterwards by the Master, whom the Doctor believes to have died.
* [[TheAbridgedSeries The Abridged Serial]]: The [[http://youtu.be/XvYC-GykB7I Dangerous]] [[http://youtu.be/lpHbuKxSzhA Assassin]].
* AsYouKnow: The Time Lords talk a lot about things they all should know, just so the viewers can understand.
* BatmanGrabsAGun: The Doctor grabs a gun trying to save the president.
* BattleInTheCenterOfTheMind: Goth and the Doctor's fight in the Matrix, though portrayed as a physical one, is really a contest of wills.
* BBCQuarry: The inside of Goth's mind, apparently.
* BloodierAndGorier: Goth shoots the Doctor twice, both with bloody results.
* BlowGun: Used by the Doctor agains the assassin.
* BondVillainStupidity: The Master could easily have killed both the Doctor and Spandrell, but instead merely stuns them so that they can witness his victory, perfectly in character.
* BrainwashedAndCrazy: As usual, the Master makes easy pawns of lesser minds. Goth seems to be working with him of his own volition, but later suggests he too was the victim of mental manipulation.
* ChalkOutline: The President. Complete with an outline of his hat.
* ClothingDamage: Both the Doctor and Goth's clothes get ripped a lot in the Matrix.
* DarkerAndEdgier: The dark echoes of the Kennedy assassination and the Red Scare, the more visceral than usual violence, several shocking cliffhangers, and the fact that Master is now a Hammer Horror monstrosity drew particular ire from MoralGuardians at the time.
* DepartmentOfRedundancyDepartment: The title, though varying definitions of whether regeneration constitutes "death" muddles this.
** It's also been pointed out that there are many incompetent assassins, so they wouldn't necessarily be deadly.
* DramaticIrony: The Time Lord authorities make deductions from the Doctor's history that lead them to believe him far more knowledgable than he actually is.
* EvilChancellor: Goth.
* EvilCripple: Since he can't regenerate, the Master has artificially extended his life and is just kind of...rotting.
* FamilyUnfriendlyDeath: Runcible's impalement.
* [[ForgotAboutHisPowers Forgot About His Ability to Regenerate]]: Quite a few Time Lords/Gallifreians in this episode seem to have forgotten they have the ability to regenerate and save themselves from permanent death.
** Though it's possible those who are [[spoiler: shrunk by the Master may have an excuse.]]
* FunWithAcronyms: The Celestial Intervention Agency.
-->"I think he's ruthless and determined; a typical CIA agent."
* GoodCopBadCop: The Doctor says, "I see: the 'hot and cold' technique" after being interrogated.
* GothicHorror: A staple of Tom Baker's tenure. Though the plot is TheManchurianCandidate, the atmosphere and visual borrows a lot from ThePhantomOfTheOpera and HammerHorror.
* TheGuardsMustBeCrazy: Lampshaded by Spandrell's criticisms of Commander Hilred for allowing the Doctor to escape:
-->'''Spandrell:''' ''Well done, Hilred. An antiquated capsule, for which you get adequate early warning, transducts on the very steps of the Capital. You are warned that the occupant is a known criminal, therefore you allow him to escape and conceal himself in a building a mere 53 stories high. A clever stratagem, Hildred. You're trying to confuse him, I take it?''
* HeroTrackingFailure: Multiple times in the Matrix.
* HeroWithBadPublicity: Unfortunately that Omega business was covered up, so the Doctor is known only as a disgraced exile apparently linked to a despised 'dirty tricks' agency.
* HuntingTheMostDangerousGame: Goth's pursuit of the Doctor in the Matrix has heavy shades of this.
* ImprovisedWeapon: The Doctor fashions a blowgun out of a bamboo stalk, a thorn and an almost empty bottle of poison.
* InTheStyleOf: The DVD's "behind-the-scenes" subtitles reveal that this story is a pastiche of "film-noir detective" stories; Spandrell is the Time Lord version of the "antacid-gobbling" police chief.
* JohnFKennedy: The assassination of the president (note the use of the American executive title rather than "prime minister," as one might expect from a BBC show) has obvious and intentional resonance with the Kennedy murder.
* JustAFleshWound: In the Matrix, the Doctor gets shot in the leg and arm but he can perfectly use them after he's bandaged them. Same case with Goth, who gets shot in the stomach and doesn't seem to have any trouble with it once he's bandaged.
* LoopholeAbuse: The Doctor is accused of killing the President of Gallifrey, the punishment for which is execution. However, the president had not named a successor before he was killed so an election must be held. So to put off his execution long enough to figure out what's really going on, the Doctor invokes some obscure law that lets him ''submit himself as a candidate'' so the Time Lords can't execute him until after the election.
* ManipulativeBastard: The Master is, perhaps miraculously, even more underhanded than usual here.
* TheMaster: Is a decaying husk of a Time Lord.
* MonsterClown: A brief (but memorable) glimpse in the Matrix.
* MoralGuardians: Another one to incur the wrath of Mary Whitehouse, due to the cliffhanger where the Doctor apparently drowns.
* NiceHat: The Time Lord's iconic headpieces debut in this serial.
* NotSoHarmlessVillain: The show's new producer considered the previous incarnations of the Master a "Comic-opera villain" and wanted something conspicuously scarier and more threatening for his return. Well, it worked...
* NotSoOmniscientCouncilOfBickering: The Time Lords in this story are a group of pompous, senile old men who have mostly forgotten how to use their sufficiently advanced technology.
* OffTheShelfFX: An Action Man doll doubles as a matter-condensed Chancellery Guardsman. Also, the "transduction" effect used on the TARDIS was reused from ''SwapShop''.
* OffOnATechnicality: In a rare heroic case, the Doctor offers himself as a presidential candidate so he can not be tried before the elections.
* OhCrap: Upon seeing the technician's shrunken corpse stashed in the telescope, the Doctor instantly recognises it as the work of TheMaster and turns very grave.
* OpeningMonologue: Not used again until the TV movie.
* OpeningScroll: The only story in the series to use one.
* ThePardon: The traditional practice at the opening of a presidency; the Doctor's trial is rushed so he can be executed before the question of whether to spare a brutal murderer or to ignore tradition arises.
* PhlebotinumBreakdown: As the Doctor points out, if the sash really made you invincible then the Master's assassination plan wouldn't have worked in the first place.
* PinchMe: The Doctor is briefly able to avoid Goth's traps in the Matrix by denying that they exist. Unfortunately, the projection is so strong that the Doctor can't resist for long and has to fight back on Goth's terms.
* PlatonicCave: The Matrix.
* RebelliousSpirit: The Doctor spends his entire trial doodling caricatures of his accusers.
* RedScare: The story is noticeably steeped in fears of subversion from within, treachery from trusted public servants, the duplicity of men in power, and the decay (literally, in the case of the Master) of idealism.
* ResistanceIsFutile: The Master says this verbatim.
* SesquipedalianLoquaciousness: Borusa uses a lot of big words.
* ShoutOut: The biplane that menaces the Doctor is reminiscent of the crop duster from ''Film/NorthByNorthwest''.
* SomethingCompletelyDifferent: This is the Doctor's only twentieth-century TV solo story with no companion in tow. This was ultimately deemed undesirable in the long run, although it would be revived occasionally in the 21st century, in particular in Christmas specials.
* TechnicolorToxin: In the Matrix sequence, the poison Goth pours into the only source of drinking water is green.
** OffTheShelfFX: In fact, it looks very much like green food colouring, still in its original bottle.
* ThoseTwoGuys: Spandrell and Engin.
* TorturePorn: The Doctor gets ''very'' thoroughly tortured.
* WholePlotReference: The story owes no small debt to ''TheManchurianCandidate'', and the DVD release has a featurette specifically about this.
* YearInsideHourOutside: Time runs more quickly in the Matrix. The Doctor's adventures take up an episode and a half; to the Time Lords watching, it takes about four minutes.
* YouLookFamiliar: Chancellor Goth is played by Bernard Horsfall, who also played the Time Lord who sentenced the Doctor to exile in "[[Recap/DoctorWhoS6E7TheWarGames The War Games]]". Some [[Franchise/DoctorWhoExpandedUniverse Expanded Universe]] works make them the same character, but he wasn't cast with this in mind.