You have vital data so dangerous that there must be absolutely no chance of it falling into the wrong hands. Where do you hide that data?

You bury it in someone's mind.

Burying data in a person's subconscious as a result of a post-hypnotic suggestion is a common MacGuffin in sci-fi and spy thrillers. Very often, the person will have no idea of what he's carrying around, usually by design. Also expect that the person will be someone you'd least suspect. Could be a child or a fool; it could even be the hero who was unaware that he was carrying what he sought all along. Frequently used to create the ManchurianAgent.

Compare the various amnesia tropes, such as CriminalAmnesiac and EasyAmnesia. See also NeuralImplanting, another method by which this can be done, and also MemoryJar. Contrast AlternateIdentityAmnesia.

May result in MySkullRunnethOver. This may be the result of a time delayed ExpositionBeam. If you're doing it to yourself, it's usually part of a MemoryGambit.




[[folder:Anime & Manga]]
* Dolls in ''Anime/DarkerThanBlack'' can be used for this.
%%* The Whispered in ''LightNovel/FullMetalPanic''.
* [[spoiler:Lain herself]] in ''Anime/SerialExperimentsLain''.
* Index Librorum Prohibitorum from ''LightNovel/ACertainMagicalIndex'' received her name from the fact that she was forced (using her photographic memory) to memorize 103,000 magical grimoires.

[[folder:Fan Fiction]]
* In the ''Anime/DragonballZ'' story FanFic/HonorTrip, [[AlmightyJanitor Enma Daiou]] has a surprisingly labyrinthine mind that not even [[spoiler: Future Cell]] could crack to obtain knowledge of Otherworld's various barriers.
* In the LightNovel/HaruhiSuzumiya fanfic ''Fanfic/KyonBigDamnHero'' Mikuru keeps a collection of recorded memories for reference when she has to return to her own time.
** Technically, Haruhi does this to herself, locking herself out of the knowledge of her own [[RealityWarper powers]], complete with [[TrustPassword key]].

* ''Film/JohnnyMnemonic'', loosely based on Creator/WilliamGibson's short story of the same name. Where the protagonist is a "courier" who carries data securely in a cranial implant.
* ''Film/FlightOfTheNavigator'' was about a little boy that had all sorts of star charts from aliens temporarily stored in his brain, and was later picked up for retrieval when the alien robot accidentally lost its own copies.
* Used as the hook to bring Agent K back from being neuralyzed in ''Film/MenInBlack II''.
* In ''Film/StarTrekIIITheSearchForSpock'' the viewers discover that at the end of the previous movie, Spock placed his soul in Doctor [=McCoy=] just before his HeroicSacrifice.
* ''Series/MysteryScienceTheater3000'' alum ''Film/OperationDouble007'' spent its first half chasing after a woman who had been given sensitive information by a deceased operative. The trick was, it had been given to her while she was under a certain kind of deep hypnosis, and could only be retrieved if she was put back under in the exact same way.
* Sebastian Rook does this on himself in ''Film/{{Cypher}}''. He overwrote his own personality so he could become [[spoiler:the meekly protagonist Morgan Sullivan and steal a specific data file from the vault of a MegaCorp, then reset himself.]]
* The entire mission of the ''Film/{{Inception}}'' is to do exactly this, though instead of information, the goal is to implant an idea. As well, Browning suggests that Fischer Sr. may have done this to his son in the first dream layer.
* In the ''Film/TotalRecall2012'' remake, Quaid learns that he has [[spoiler: the global shutdown codes for the Synth army]] locked away in his head from his time as Hauser, and must get this back to the Resistance. [[spoiler: Though it is actually a tracking signal for Cohaagen to follow back to the resistance base.]]
* A literal case in ''Film/{{Elysium}}''. After Greg Carlyle uploads [[spoiler: the reboot code to the space station of the same name]] to an implant in his brain, encrypts the program, and smashes the computer it came from, several of the characters are feverishly after that code when the protagonist Max steals it from Carlyle, [[spoiler: so that the people on Earth can be allowed to go to the station]]. But the encryption software kills whoever holds the item after transfer, and once it's modified at the end, Max dies.

* In ''Literature/{{Fahrenheit 451}}'' the secret society of readers [[spoiler: use PhotographicMemory techniques to memorize books so they can be written again once the book-burning government dies in the coming nuclear war.]]
* In ''Literature/TheHitchhikersGuideToTheGalaxy'':
** Zaphod buries the [[spoiler: location of the man who rules the universe]] within his brains.
** Because in this universe Earth is [[spoiler: a supercomputer designed to find the Ultimate Question of Life, the Universe, and Everything]], all Earthlings have [[spoiler: the Question]] imprinted in their subconscious.
* In ''Abarat'' by Clive Barker, an important key is hidden in Candy's mind, despite its apparently being a physical object.
* From ''Literature/MidnightAtTheWellOfSouls'': Vardia Diplo 1261 is, for the most part, a human cassette reel -- a NeuroVault with legs. A message is encoded in her head, to be shuttled to another planet's embassy, where the vault is unlocked, and she's basically written over with the base "Diplo program".
* In ''Literature/ManWalksIntoARoom'', a group of scientists attempt to implant a memory from one person into the protagonist's brain. The memory itself, to the scientists, is only important in that it's a strong, easily distinguished, distinctive memory, not in terms of its content: [[spoiler: a nuclear weapons test occurring too close to a group of soldiers]].
* Haruki Murakami's ''Hard-Boiled Wonderland and the End of the World'' is about a man whose subconscious is used to store classified data in a cyberpunk future.
* ''Literature/ForgottenRealms'' has its share of memory transfers, but specifically in ''Return of the Archwizards'' the wizard spy dropped lots of reconnaissance data (for all the audience knows, it could be ''centuries'' worth of examining SealedEvilInACan while hiding inside the same can) to another guy, because he was dying and it was the only way to save priceless knowledge. [[spoiler:Carrier used this memory only as provoked "I just feel it must be so" insights, even after he understood what's going on (which still made him so valuable that dead wizard's boss could neither let him go nor kill him, nor even use outright [[BrainWashed mind control]]).]]
* In ''Literature/TheSearchForSnout'' by Creator/BruceCoville, it's revealed near the end that the main character has a secret piece of data in his brain that will allow the villain to literally destroy time.
* In Creator/RobertAHeinlein's ''Literature/CitizenOfTheGalaxy'', Baslim hypnotizes his foster son Thorby into memorizing a coded final report to the SpacePolice, as well as a message to a ship's captain to help Thorby escape off-planet.
* In Heinlein's ''Literature/IfThisGoesOn'', Lyle is told he has been given critical information that he has to get to LaResistance. When he gets there he is put under anesthesia to extract the information. He later asks one of the Resistance scientists what was the nature of the "really important" message. He is disappointed when he is told that it was just lots of routine information. The scientist realizes he made a mistake, the man did have very important information. He also had his resistance credentials, "If they hadn't checked out, you would never have woken up."
* This is pretty much the entire premise of ''One of Us'' by Creator/MichaelMarshallSmith. The main character makes his living storing memories that others want to get rid of temporarily -- for instance, a businessman about to screw over his partner hands over a memory of a moral lesson from his father. (Permanently destroying a memory screws up TheForce.) Unfortunately for him, someone figures out that this can work as LaserGuidedAmnesia for the giver, and that the BigBad only wants to kill anyone who ''remembers'' a particular secret.
* In Creator/PiersAnthony's Macroscope, [[spoiler:Brad Carpenter]] hides [[BlackmailIsSuchAnUglyWord information]] about Schon inside [[spoiler:Afra Summerfield's]] mind.
* In ''Literature/SwordOfTruth'', Richard's adoptive father had him memorise a book, destroying it after he was satisfied that Richard could recite it verbatim. The first book of the series revolves around the BigBad's attempts to extract this information from him.
** There is also another example, when Richard prevents himself from going fully mad due to ColdBloodedTorture by locking away the core of his personality.
* The ''distrans'' of the ''Franchise/{{Dune}}'' universe is used to encode messages in the voices of bats and birds. It can be used on humans, but it is frowned upon. So naturally both the protagonists and antagonists make use of human distrans.
* The Amnesia Arc in the Literature/EighthDoctorAdventures (and the EDA series itself) ends with the revelation that [[spoiler: the Doctor's amnesia was caused by downloading the ''entire Time Lord matrix'' into his mind, thereby enabling Gallifrey to be restored from backup at a future date]].
* In ''Literature/TheJenniferMorgue'', Bob Howard has the briefing for the next stage of his mission implanted this way. Unfortunately the circumstances change halfway through the book, so thanks to this trope Bob is forced to endure an InfoDump that's no longer relevant.
* Tracer from ''Literature/FloatingPoint'', being a [[ArtificialIntelligence living A.I.]] in a [[InsideAComputerSystem digital world]], was able to install one of these to help him sort and cross-index his memories. [[spoiler:Also quite handy for [[MemoryGambit erasing memories]] he doesn't find pleasant.]]

[[folder:Live Action TV]]
* ''Series/BlakesSeven''. The location of Star One (the MasterComputer that runs the Terran Federation) is buried in the mind of the King's Fool on a primitive planet.
* The whole premise of ''Series/{{Chuck}}'' - the Intersect is an incredibly comprehensive espionage database so important it can't be trusted to a computer ([[FridgeLogic or, apparently, spread among many computers]]) so it's uploaded to the mind of a master-spy. Unless it should accidentally be uploaded into that master-spy's college roommate...
* ''Series/{{Firefly}}''. In this case, it turns out to have been entirely accidental, and those whom the information concerns [[HeKnowsTooMuch want to keep it under wraps]].
* Played for three years and TheMovie of ''incredible'' dramatic effect in ''Series/{{Farscape}}''. John Crichton has the secret to wormhole technology buried in his mind by SufficientlyAdvancedAliens. The idea is that John doesn't ''know'' he has this dangerous information (which could be used to alter reality or create a DoomsdayDevice) but his subconscious knowledge will give him an 'instinct' for wormholes that will help him get back to Earth. Unfortunately this fact is uncovered by the BigBad Scorpius, who spends the rest of the series trying to rip the knowledge from Crichton's head.
* O'Neill frequently gets his head packed full of deadly amounts of [[LostTechnology Lost Wisdom]] from [[{{Precursors}} The Ancients]], barely surviving long enough to get it extracted by the Asgard on ''Series/StargateSG1''.
* Donna Noble on ''Series/DoctorWho'' is a variation on this trope. [[spoiler:She has Time Lord knowledge embedded in her brain, and for her own well-being she had to lose all her memories of the time spent with the Doctor. If she were ever allowed to remember him or her adventures all over the universe, it would destroy her.]]
* In Harper 2.0 of ''Series/{{Andromeda}}'' Harper gets the largest library in the universe downloaded into his brain. This slowly begins to burn up his brain until he gets rid of it. It's used for a ContinuityNod later when trying to remember where he hid some of the data.
* In ''Series/{{Fringe}}'', William Bell removed pieces of [[spoiler:Walter]]'s brain and put them into other people's brains in order to prevent information about [[spoiler:how to get to the other universe]] from falling into the wrong hands.
%% * ''Series/DarkAngel''

[[folder:Tabletop Games]]
* ''TabletopGame/{{Shadowrun}}'' has the "Data lock" implant, which is clearly a ShoutOut to Johnny Mnemonic.
* ''TabletopGame/EclipsePhase'': "Hidden Knowledge" psychosurgery conceals information somewhere in a character's mind until released with a trigger word. Or more psychosurgery.
* In ''TabletopGame/VampireTheRequiem'', a vampire can learn to conceal information inside a messenger's {{blood|Magic}}.

* In ''Theatre/The39Steps'', the top secret information the bad guys are trying to smuggle out of the country is hidden in the mind of the "Memory Man", a showman who has [[PhotographicMemory the ability to take in such information.]]

[[folder:Video Games]]
* It's [[{{Fanon}} commonly agreed]] that the player character in ''VideoGame/{{Marathon}} Infinity'' smuggles [[AIIsACrapshoot Durandal]] across timelines within his own brain toward the end of the game.
* Jake in the SNES ''VideoGame/{{Shadowrun}}'' game has some sensitive files in his head computer, which starts off locked until an attempt to repair it sets off a [[WhyAmITicking Cortex Bomb]]. This is, of course, perfectly normal within the confines of the Tabletop Game.
** It's implied that Jake did not undergo the procedure willingly, as a character met earlier on notes that the head computer and datajack are new additions. Jake himself has complete amnesia, though.
* ''VideoGame/{{Xenosaga}} Episode III'' uses this in an interesting way. [[spoiler:The Godwin sisters hold the two parts of the unlock code which opens the Zohar Emulator storage. Both are aware of this, and didn't require any messy mind tricks -- their minds already had uplink ports from their previous "jobs" before the ''Durandal''.]]
** The Realian MOMO has the politically and functionally dangerous Y-Data stored in her head.
** ''Xenosaga'' does this a lot, actually; Canaan, another Realian, likewise has part of the Y-Data dropped into his head; he's blocked from accessing it, which makes him ''very grumpy''. He spends the better part of fifteen years trying to get it out and failing.
* Asimov, the hero of ''VideoGame/MrRobot'', saves his friends from being permanently scrapped by downloading their brainmaps into his system. Conveniently enough, this is also how you add members to your party for hacking missions.
* A variant in ''VideoGame/KnightsOfTheOldRepublic''. Your character was getting Force visions and flashbacks of an allegedly-dead Sith Lord named Revan, leading both Bastila and themselves to Star Maps that will reveal the location of the Star-Forge. [[spoiler: However, it turns out that Revan isn't entire dead [[TomatoInTheMirror as everyone thought]].]]
** A relatively minor one, galactically speaking, is Consular companion Felix Iresso in ''VideoGame/StarWarsTheOldRepublic.'' A Force-insensitive Republic grunt, he and his buddy were captured by the Sith and had a Sith holocron forcibly downloaded into their heads because the crazy Darth did not want to share the contents with the rest of the class. Iresso's pal went insane, but Iresso seems relatively normal. No, he can't access the contents, and doesn't much want to.
* In ''VideoGame/MassEffect1'', Matriarch Benezia does this to herself to avoid being completely [[MindControl indoctrinated]]. It works long enough for her to give vital information to the protagonists, before the indoctrination reasserts itself.
** Due to both the Prothean Beacon and the Cipher, Shepard has the experience and collective knowledge of the entire Prothean race implanted within their subconscious mind, which leads them eventually to Ilos. It's also the key to waking Javik in ''3''.
* Goal from ''VideoGame/{{Deponia}}'' stores some important codes along with her consciousness in her implant.
* ''Franchise/KingdomHearts'' has Sora, whose memories are nearly constantly used for this.
* In ''VideoGame/{{Galerians}}'', the protagonist and MacguffinGirl heroine have programs stashed in their heads by their parents. The programs are the key to destroying an A.I their fathers created which slipped its leash [[AIIsACrapshoot to supplant the human race with its own creations.]]

[[folder:Web Comics]]
* ''Webcomic/{{Homestuck}}'': The genetic code for the creation of a first guardian is locked away within the minds of one or more players, who end up writing it on their walls and in a book. It winds up being unlocked by some sort of important event. In the kid's session, Rose wrote it in one of her journals, while in the troll's session [[spoiler: it was unlocked via the infamous Team Charge debacle, and authored by Tavros, Aradia, Vriska, Terezi, and a doomed timeline Gamzee, who wrote it in their [=FLARPing=] manuals and Karkat's ~ATH book.]]
* ''Webcomic/TheOrderOfTheStick'': Redcloak appears convinced the paladins of the Sapphire Guard had pulled this, though he seems to have been wrong. Redcloak himself has his own NeuroVault with [[spoiler: the divine part of the ritual to 'control', really 'transfer control' of the Gate's position to his deity, imparted to him by the Red Mantle. It qualifies as it was never commited to paper.]] It's not that far of a stretch for him to expect opposing forces to use the same kind of trick. Torturing O'Chul for information was also [[DragonWithAnAgenda Redcloak]]'s excuse for staying in Azure City.
* In ''Webcomic/SchlockMercenary'', the eponymous carbosilicate amorph [[ pulls one of these]]: since his entire body acts as a "brain", forming a neuro-vault is as simple as collecting all the tissue that stores the information and scooping it out for safekeeping.

[[folder:Western Animation]]
* In ''WesternAnimation/BeastWars'', Blackarachnia purposely downloads the data on the golden disks, which were stolen by Dinobot, and which contain [[spoiler: the entry code to the Ark]] into her own brain and destroys the computer containing the original copy so that Megatron can't use it.
* ''WesternAnimation/CodeLyoko'': Franz Hopper hid the "keys to Lyoko" that XANA would need to escape inside himself and Aelita.
* ''WesternAnimation/GIJoe'', "There's No Place Like Springfield": Plans for a deadly super-weapon are implanted into Shipwreck's head, and can only be retrieved if a certain code word is spoken to him. Cobra conducts an [[FakedRipVanWinkle elaborate ruse]] to try and figure it out.
** And even then, the code turns out to be a code ''phrase''. [[spoiler:("Frogs In Wintertime")]]