[[quoteright:252:http://static.tvtropes.org/pmwiki/pub/images/Eisenhorn_cover_2_8835.jpg]]

->''Most perturbatory.''
-->-- '''Uber Aemos'''

''Eisenhorn'' is a trilogy of novels by Creator/DanAbnett set in the ''TabletopGame/{{Warhammer 40000}}'' universe, following the adventures of [[StateSec Inquisitor]] Eisenhorn and his [[TrueCompanions retinue]] as they combat the enemies of the [[TheEmpire Imperium of Man]]. Throughout the books, Eisenhorn finds himself having to use increasingly desperate and dangerous means against his foes.

The first book, ''Xenos'', starts with Gregor Eisenhorn and his crew pursuing a heretic in a seemingly routine task when they uncover a mysterious artifact bearing the preserved mind of the heretic Pontius Glaw. In the subsequent investigation, Eisenhorn and crew find themselves embroiled in a heretic group's plan to contact aliens for a demonic text.

The second book, ''Malleus'', begins with a major celebratory parade ruined by Chaos-linked renegades. The pursuit of these enemies leads to Eisenhorn uncovering and defeating a much-revered Inquisitor gone to Chaos.

The third book, ''Hereticus'', sees Eisenhorn pursued by allies of [[spoiler:Glaw]] and his attempt to stop [[spoiler:Glaw]] from acquiring a world-ending power.

There are also two short stories available, both of which can be found in the [[{{Doorstopper}} doorstopping]] [[{{Anthology}} omnibus]] edition. A spin-off trilogy, ''Literature/{{Ravenor}}'', has been published and Dan Abnett has begun a third "Bequin trilogy", described by him as "Literature/RavenorVsEisenhorn".

In the mean time, Eisenhorn is set to appear in a set of Audio Dramas, collectively called Talon and Thorn.

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!!As part of ''TabletopGame/{{Warhammer 40000}}'', the series involves a large number of the tropes on that page, as well as employing literary and narrative tropes of its own:

* AdventurerArchaeologist: A villainous example is a minor character in ''Xenos'', though more of a PunchClockVillain.
* AlienGeometries: The saruthi "tetrascapes" in ''Xenos'', and [[spoiler:in a different way, the world of Ghul in ''Hereticus'']].
* AndIMustScream:
** [[spoiler:Ravenor]], as a result of the Thracian Gate massacre in ''Malleus''. He's basically the main character in ''Literature/JohnnyGotHisGun'', except that his psyker ability allows him to function through his force chair.
** [[spoiler:Pontius Glaw until Eisenhorn [[HonorBeforeReason (perhaps foolishly)]] has a body built for him.]]
* AnyoneCanDie: By the end of ''Hereticus'', much of the main cast are either dead or severely incapacitated.
* ArmourIsUseless: Unusually for this setting; it saves someone's life only once in the trilogy.
* AttackAttackAttack
* BadDreams
* {{Badass}}: Several. Harlon Nayl, both Betancores, Eisenhorn himself has moments (to the point where a ''SpaceMarine'' is scared of him), Cherubael, Commodus Voke, Brother Guilar [[TookALevelInBadass takes a level]], and Librarian Bryntoth (implied).
** For non-40k familiar tropers, a "Librarian" in 40k is a genetically engineered super-soldier with the power to tap into a primal chaotic force in battle. "Librarian" is their day job.
* BadassGrandpa: Technically, Cherubael qualifies, as he is thousands of years old. A more literal example is Commodus Voke - Eisenhorn describes his psychic powers as "legendary". He even stands up to a daemonhost and saves Eisenhorn's life.
** The best example is Lord Inquisitor Phlebas Alessandro Rorken - he banishes an EldritchAbomination by ''charging it with a holy flamethrower and yelling prayers.''
** Eisenhorn himself. He is in his 40's when first introduced, and by the end of the third book he is still active at over 180 years old. By the time of the Eisenhorn vs. Ravenor he is nearly 300 years old and, though physically a wreck, more dangerous than ever.
* BadassCape: [[spoiler:Pontius Glaw]], in the final encounter with him, wears one made of many small, very sharp blades.
* BadassLongcoat: Eisenhorn is fond of billowing overcoats, although, cover picture be damned, he's never actually mentioned as wearing two at once.
* BeautyIsNeverTarnished: Alisebeth Bequin, who manages to be glamorous and alluring even while exchanging gunfire with enemy heretics.
* BittersweetEnding: [[spoiler:Pontius Glaw's apocalyptic plan is foiled...but most of Eisenhorn's companions have been killed in the process, and he is considered a rogue and a heretic.]]
** [[spoiler: Considered nothing. He IS a rogue and a heretic. Albeit, a very well-intentioned one]]
* BrownNote: The utter, incomprehensible scale of [[spoiler:the daemon-king's tomb on Ghul in ''Hereticus'']] drives a hired gun to tears.
** In ''Malleus'' [[spoiler:being an ordinary human attending the parade...]]
** In ''Herectus'', [[spoiler: the Chaos Titan has dirge casters that blast infrasound onto the battlefield.]] For reference, infrasound is a noise that inspires unfounded fear, dread, and paranoia in those that hear it.
* CampStraight: [[IntrepidMerchant Rogue Trader]] Tobias Maxilla. A [[LargeHam flamboyant]] [[TheDandy dandy]], he flirts with every woman he encounters. Somewhat ambiguous; he is implied to be a [[RoboSexual machine fetishist]], perhaps exclusively.
** Then again, [[spoiler: his lower torso is robotic, so it's unlikely he has physical needs to attend to]]. When he has human passengers, Eisenhorn observes that he's delighted simply to have someone to show his art collections and talk to.
* CapturedSuperEntity: The Psykers whose kidnappers were responsible for the Thracian Gate atrocity in ''Malleus''. Also, the daemonhosts Cherubael and Prophaniti, to an extent.
* TheChessmaster: Both {{Big Bad}}s fall handily into this. Eisenhorn himself flirts with the trope; in many ways, he is like a Cold War spymaster, only with PsychicPowers and a [[ImplausibleFencingPowers way with a sword]].
* ClearMyName: Pretty much the entire plot of ''Malleus''.
* ColdBloodedTorture
* CombatPragmatist: Eisenhorn starts a pointless swordfight, then shoots his opponent when he starts to lose.
* ComeToGawk: The parade included displaying captives.
* CompellingVoice: Eisenhorn and other Inquisitors, through what Eisenhorn refers to as "the will", a manifestation of their psyker abilities. Agents of Chaos display this power as well.
* ContinuityDrift: At one point Eisenhorn mentions the "Primarch" of the White Consuls, by which he clearly means the "Chapter Master", but the distinction was less well established in canon back when ''Malleus'' was written, or possibly Eisenhorn just didn't know better in character.
** Also, Aemos twice mentions Tyranids in passing, while {{Ravenor}} would reveal that both stories took place before they were named or (officially) encountered.
** A couple of times throughout the trilogy, Eisenhorn makes an off-hand reference to someone 'seeing his expression of disbelief' or similar occasions. Even Dan Abnett sometimes forgets that Eisenhorn has no facial expressions, due to the result of torture that was described in detail in the first book.
* ContinuityNod: Inquisitors Heldane and {{Ravenor}} both appear in Abnett's earlier ''GauntsGhosts'' novels. Titan Princeps Hekate (from the Graphic Novel series ''Titan'') is also mentioned in ''Malleus'', albeit as an old man near retirement, which was a pleasant surprise for fans, as his own series by that point seemed to have ended in a HeroicSacrifice.
** One of Battlefleet Scarus' ships is named ''Defence of Stalinvast'', after the planet subjected to Exterminatus in Ian Watson's ''Inquisition War'' Trilogy.
** A slightly knotty one in Malleus. Eisenhorn mentions his plans to meet with a group of other inquisitors, one of which includes Defay, from the Inquisitor comic series in Warhammer Monthly. Confusingly, Defay as also mentioned in Gaunt's Ghosts, which is set many hundreds of years after Eisenhorn.
*** Not necessarily an error - in the Warhammer 40,000 universe medical technologies, cybernetics, a better diet, and drugs can keep the well-heeled alive for centuries.
*** Could also merely be another inquisitor by that name, maybe an offspring of the original. It is, after all, a vast organisation.
* ConverseWithTheUnconscious
* CrapsackWorld: For the most part averted. Although Eisenhorn visits many deeply unpleasant places during his adventures, this must be taken in context with the larger ''Warhammer 40K'' universe. Yes, there is still galaxy spanning war going on, but Imperial society is shown as functioning and, in the case of the planet Gudrun, can be extremely pleasant or at least tolerable.
** Taken straight with Hive Worlds like Thracian Primaris and Sameter.
* CrossMeltingAura: Cherubael does this to an Imperial aquila.
* CryonicsFailure
* DividedWeFall
* DreamingOfThingsToCome
* DroppedABridgeOnHim: [[spoiler:Midas Betancore]] gets this treatment between ''Xenos'' and ''Malleus''. So does [[spoiler: Nathum Inshabel, and his entire staff]] between ''Malleus'' and ''Hereticus''.
* DueToTheDead
* EldritchLocation: Saruthi tetrascapes. In the coastal regions of a tetrascape, waves break ''backwards'', and that is the least weird thing about them.
** It's implied that the Saruthi intended them to be unnerving, as they were created for the aliens to meet and bargain with other races--the Saruthi wanted to intimidate visitors to establish that they were in control.
* EmpathicWeapon: Eisenhorn's force sword, Barbarisater.
* EvilIsDeathlyCold: Frost formation often accompanies use of Warp powers.
* EyesDoNotBelongThere: In ''Malleus'', they must infiltrate muties. One mutant woman winks at them -- with an eye at the end of one tongue.
* FauxAffablyEvil: Pontius Glaw is a [[WickedCultured charming, erudite, and refined gentleman.]] Eisenhorn notes that were he not also Chaos-corrupted, the two of them would probably have been the best of friends.
* FiveManBand
* FriendlyEnemy: Cherubael to Eisenhorn, at least at first, because [[spoiler:Eisenhorn can free him from his servitude to Quixos]]. He becomes much less friendly ([[spoiler:and somewhat less of an enemy]]) later on, after [[spoiler:Eisenhorn ''re''-binds him and sticks him in storage, occasionally pulling him out to battle powerful opponents]].
* FrozenFace: Eisenhorn is left unable to make any kind of facial expression after the extensive neurological damage he suffers during Locke's ColdBloodedTorture.
* FullFrontalAssault: Cherubael and Prophaniti.
* GenerationXerox: [[spoiler:"So very Betancore... Just like her damned father." The title for that chapter is "Something Typically Betancore."]]
* GladiatorGames: Eisenhorn and company are forced into one.
* GlamourFailure: The Daemon-possessed suffer from this.
* GreatEscape
* GunsAkimbo: Midas and Medea Betancore fight with a pair of needle pistols, and Interrogator Inshabel is armed with a pair of laspistols.
* HeWhoFightsMonsters: Eisenhorn falls into this rather badly, starting out as a "conservative" inquisitor unwilling to accept that using Chaos against itself is a viable strategy. A combination of compromise and desperation, however, eventually leads him to [[spoiler:summon a Daemonhost of his own]]. Ravenor is of the opinion that Radicalism is inevitable for Inquisitors, and the only hope for them is to do as much good as they can and hope they die before JumpingOffTheSlipperySlope.
** Harlon Nayl puts an interesting spin on the concept. He tells Eisenhorn that sometimes you've got to bend and break the rules in order to win. Eisenhorn assumes that this is equivalent to "the end justifies the means". Nayl denies this, noting that confusing the two is what leads to the slippery slope.
*** FridgeLogic kicks in when you realize that ''both'' of them are trying to self-justify. The series gives us several Inquisitors of long service who don't turn radical, such as Rorken, Voke, Bezier, Neve and Ricci.
* HookerWithAHeartOfGold: Bequin when we first meet her.
* InHarmsWay
* InvoluntarySuicideMechanism: A captured mercenary has a YourHeadAsplode variant of this that goes off when Eisenhorn attempts to interrogate him.
** Later on, after [[spoiler: Eisenhorn has been captured,]] he tries dropping the same phrase that made the lackey die when in the presence of the higher-ups. [[spoiler: He didn't expect it to work, and was right.]]
* ItIsDehumanizing: Eisenhorn refers to Cherubael as an "it" while others identify him as a male. As daemons are made from the psychic manifestations of sapient beings, they can develop a dominate gender identity. However, being buddy buddy with demons is a good way to let your guard down and have your soul consumed so the trope is justified. When Eisenhorn starts referring to to Cherubael as a "he" in the ''Ravenor'' series, the titular character starts to get a little leery. Eisenhorn claims that Cherubael and he came to an understanding leaving it ambiguous to whether or not Eisenhorn has fallen or not.
* ItsAllAboutMe: Cherubael.
* LaserBlade: Eisenhorn initially owned one of the extremely rare pure energy blade power swords before he wrecked it in combat in the second book.
* [[LightIsNotGood Light]]/PureIsNotGood: In ''Hereticus'', Cherubael. Eisenhorn lampshades it.
* LawfulStupid: You'd be astonished how easily Inquisitors get caught by this.
** And ''Christ,'' does the witchhunter in Malleus fall under here. His ''first appearance'' is him [[spoiler: trying to execute Eisenhorn for heresy (though saving his life in the process) on absurdly stupid charges.]] Eisenhorn shortly thereafter recounts a mission where twenty-odd newly discovered psykers, all under 14 years old, were abducted by raiders before the Black Ships could pick them up. Seeing that psykers are ''extremely'' rare, and even rarer to find at such young ages, Eisenhorn launches a mission to rescue them...while the witchhunter decides that kidnapping classifies them all as witches that are in dire need of execution.
*** Not only are psykers very uncommon but the reason that the Imperium sends Black Ships to collect them in the first place is because they're literally necessary for space ships and the Emperor to continue functioning. They're distinctly worth rescuing for all sorts of warm and cold hearted reasons.
** Considering how dangerous a psyker can be, executing a psyker rather than potentially bringing a trojan TykeBomb into a secure location may be the smarter move. And while said witchhunter was (arguably) mistaken at the time, it is hard to deny that Eisenhorn became exactly what he feared by the end of the series.
* MercyKill: Invoked as Eisenhorn explains why he could not do it to the dying victims at the opening of ''Xenos''.
* MinorCrimeRevealsMajorPlot: Done [[UpToEleven as only 40K can do it]]. The first chapter has Eisenhorn hunting a traitor with ''thousands'' of murders on his record, not to mention innumerably more acts of smuggling, sabotage, and theft, who is nevertheless only a tiny cog in the grand scheme. It gets much bigger from there.
* NewMeat: Subverted in ''Xenos''
* NoGoodDeedGoesUnpunished: [[spoiler: Eisenhorn arranges for Pontius Glaw to be given a mechanical body in return for his guidance on how to create a daemonhost. This turns out to be a very, very, ''VERY'' bad move.]]
** A milder example in the audio dramas. Master Immus, a clerk who has been used as a pawn in a heretical scheme, goes to a young Eisenhorn and confesses. After a long night of interrogation and mild mind rape, Eisenhorn comes to the conclusion that Master Immus is completely innocent of any involvement in the scheme and is grateful that a man did his Imperial duty by coming forward. The sentiment is decidedly one sided though because it results in the man's place of work being permanently shut down, every employee without a reference or any means of social support.
* NWordPrivileges: Mutants being called "twists."
* ObviouslyEvil: Discussed in-story with regards to the [[TomeOfEldritchLore Necroteuch and Malus Codicum]]. The Necroteuch is obviously dangerous from the get-go, as it's ''sentient'' and overtly attempting to take control of its holder's mind and force their submission to Chaos. The Malus Codicum, on the other hand, is just a small black book. [[ParanoiaFuel A nondescript, unremarkable book that one might find anywhere]]. Over the course of the series, Eisenhorn starts getting paranoid that the Malus Codicium may also sentient and, if so, is exerting its influence much more discreetly. Naturally the latter is much more dangerous.
* OnceMoreWithClarity - In ''Hereticus'', Eisenhorn and [[spoiler: Ravenor]] hold an auto-seance to see what [[spoiler: Pontius Glaw]] was up to on a planet. They watch a scene with him and an orgyn and a man with an auphex, but they can't tell what they are doing. Eisenhorn tells the astropaths to expand the area of the seance and they see that [[spoiler: Pontius was performing an auto-seance as well. The Farseer then helps reveal what Pontius saw which made the scene make more sense.]]
* ThePiratesWhoDontDoAnything: While he can hardly be accused of "not doing anything," Eisenhorn is The Ordo Xenos Inquisitor Who Doesn't Deal With Aliens Very Often. Mostly because he keeps getting distracted by heretics, daemonhosts, other Inquisitors, and his own past decisions come back to bite him in the ass. Is there a variant for "The Pirates Who Don't Do Anything Related to Piracy"?
** Though his allegiance to the Ordo Xenos might explain why he was so sensitive to Ravenor's remarks about the virtues of the eldar.
* PunnyName: Prophaniti.
* RagtagBunchOfMisfits: Eisenhorn's retinue. Included in their number: a gunslinging pilot, an aging scholar who's literally addicted to knowledge, an ex-cop, an anti-psychic prostitute, and a flamboyant starship captain. And that's just the ''first'' novel.
* {{Revenge}}
* RightHandVersusLeftHand: Eisenhorn regularly finds himself pitted against other Inquisitors with ideological stances either more [[KnightTemplar conservative]] or [[WellIntentionedExtremist liberal]] than his own. He states outright that his possession of the [[spoiler: Malus Codicum]] would prompt half the Inquisition to try and kill him for having it and the other half would do the same in the hopes that ''they'' could get their hands on it.
* ScarsAreForever: The torture in ''Xenos'' produced permanent and noticeable nerve damage. Suffice to say, Gregor cannot smile anymore.
** Also an example of CursedWithAwesome - it comes in handy when Eisenhorn is trying to conceal his emotions.
* ShoutOut: Eisenhorn lost his virginity to a maid in his boarding school, at the age of sixteen. Like a certain other notable [[Literature/JamesBond intelligence agent]]...
* TheSmartGuy: [[DeconstructedCharacterArchetype Deconstructed]] with Aemos' meme-virus, which leads him to [[spoiler:memorize the whole of the ''Malus Codicum'']].
* {{Spinoff}}: Interrogator Ravenor, a supporting character in the ''Eisenhorn'' books who was pretty much developed from a [[ChekhovsGunman namedrop]] in the ''GauntsGhosts'' series, later became the protagonist of his own novel series. ''Eisenhorn'' itself is a spinoff of the ''TabletopGame/{{Inquisitor}}'' GaidenGame to ''TabletopGame/{{Warhammer 40000}}'', and the first novel was released concurrently with the game itself.
* StarCrossedLovers: [[spoiler:Eisenhorn and Bequin.]]
--> [[spoiler:'''Eisenhorn:''' I was a [[PsychicPowers psyker]], she an [[AntiMagic Untouchable]]. That way pain and madness lay.]]
* StrangeSyntaxSpeaker: The first book gave us the alien Saruthi, who did this when they spoke [[strike:English]] Gothic. Ironically, that was probably the [[StarfishAliens least strange]] thing about [[EldritchAbomination them]].
* TakeUpMySword: Voke invokes this in ''Xenos'', asking Eisenhorn to take over his protege if he actually does die. [[spoiler:He doesn't, at least not then.]]
* TaughtByExperience: After Cherubael defies him a few times to his great cost, Eisenhorn has the latest form triple-bound, reducing its power but making it much more docile.
* TearsOfFear When confronted with some of the more terrifying aspects of Chaos such as the Chaos Space Marines armour or [[spoiler:the tomb on Ghul.]]
* TellMeAboutMyFather
* ThemeNaming: The three novels are titled after the major Ordos of the Inquisition.
* TomeOfEldritchLore: The ''Necroteuch'' and ''Malus Codicum''.
* ToThePain: In ''Xenos''.
* TraintopBattle: In ''Hereticus'', though the supposedly super-fast train was thankfully immobile at the moment.
* TrueCompanions
* VengeanceFeelsEmpty: In ''Hereticus'', after the death of the man who killed her father, Medea realizes that her desire for {{revenge}} was really displaced desire to have known her father. (She asks Eisenhorn to [[TellMeAboutMyFather tell her about her father]]).
* VillainCorner
* VillainousBreakdown: Pontius Glaw has [[spoiler: a fatal one when Eisenhorn burns the Malus Codicium.]] Cherubael has an understated one when Gregor [[spoiler: binds him again in the second book.]]
* WellIntentionedExtremist: A vital theme throughout the series, and a central part of the last two books. As an Inquisitor, Eisenhorn is this by definition. He starts out with more emphasis on the "Well Intentioned" side and ends up with more on the "Extremist."
** And then an even further confusion is heaped on that judgment when you understand that the people declaring him to be a heretic are overwhelmingly {{Knight Templar}}s, with periodic sprinkling of LawfulStupid.
* WickedCultured: Pontius Glaw.
* WorthyOpponent: Between Eisenhorn and Glaw.
* WouldNotShootAGoodGuy Brutally averted in ''Malleus'' where Eisenhorn is forced to kill Arbites and Inquisitors who believe him to be a heretic.
* WreckedWeapon: Actually vital in stopping ''Malleus'''s BigBad.

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