Uh-oh. The {{Masquerade}} that you've worked so hard to build and maintain has suddenly been [[BrokenMasquerade broken]]. Now a bunch of {{Muggles}} know that you and your entire family are vampires/werewolves/witches/what-have-you. But no problem. All you've got to do is whip up some mojo and give them a handy case of LaserGuidedAmnesia, right?

Well, no. See, turns out your spell/hypnosis/whatever, didn't work the way you'd intended. Sure, maybe it wiped the memory of a few, but there was this one guy whose memory remained intact. (Probably TheHero or someone close to him, but most certainly a character who has relevance to the plot. This trope is not wasted on minor characters.) For another a variation, the character in question may have their memory mostly wiped, but retain some crucial piece of information relating to TheMasquerade. (Which they may not immediately recognize the significance of.)

FakeMemories usually have similar problems, someone ''always'' finds the holes.

The "partial erasure" version can result in a IKnowYoureInThereSomewhereFight attempt by a friend who tries to get the amnesiac to remember.

Compare RippleEffectProofMemory, which may overlap, and GlamourFailure. Contrast LaserGuidedAmnesia, which is when the mojo works.

!!Examples
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[[folder: Anime And Manga ]]

* In ''RahXephon'', the Mulian mind control is shown to be imperfect when Hiroko realizes she has forgotten something really important when she meets Ayato again after his disappearance.
* Some of the girls from ''Manga/TheWorldGodOnlyKnows'' remember stuff after Elsie erases their memories. They usually come up with their own version of what happened to explain. This is explicitly because New Hell has power issues, and only erases the absolute minimum. This can bite Keima in the ass; for example, he took a girl to an amusement park for a date, which ended in a kiss. According to her memories, he ditched her halfway through for no reason whatsoever.
* When [[spoiler:Albert Maverick {{Unperson}}s Kotetsu before framing him for murder]] in the 20th episode of ''TigerAndBunny'' he slips up and misses mind-wiping two crucial individuals, [[spoiler:Kotetsu's former boss Ben Jackson and judge Yuri Petrov/vigilante Lunatic]]. Both turn out to be vital in helping [[spoiler:Kotetsu avoid capture by his former friends]].
* In ''CodeGeass'', [[spoiler: after having her memory wiped twice (once by different people) Shirley regains her memories after accidently being hit by Jeremiah Gottwald's new [[AntiMagic Geass Canceler]].]]

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[[folder: Comic Books ]]
* The ending of ''CrisisOnInfiniteEarths'' shows that only the Psycho-Pirate remembers the multiverse or the details of the Crisis itself. Everyone else only has vague memories of a big battle and the skies turning red. He apparently attempted to inform people of what actually happened, only for people to assume he's insane, so they sent him to a mental institute.
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[[folder: Film ]]

* ''Film/MenInBlack'': When J meets Dr. Weaver in the Morgue, they vaguely notice that they may have met before, but dismiss it as Deja Vu. In the beginning of the movie, they had met, but K had wiped both of their memories.
** It's mentioned previously that a neuralizer leaves one feeling a vague sense of deja vu.
* ''Film/XMenFirstClass'': [[spoiler: At the end, Xavier (at least apparently) wipes [=MacTaggert's=] memory to keep the mutants safe from the [=CIA=]. All [=MacTaggert=] remembers is a few glimpses of leaves and Xavier kissing her.]]
* The protagonist of ''Film/{{Paycheck}}'' has glimpses of what he was supposed to forget, along with the envelope full of [[NoteToSelf notes]], apparently because his last job used chemicals instead of the usual neuron-zapping, which is apparently complete.
* Jack in ''Film/{{Oblivion 2013}}'' has dreams of New York before the Scav invasion, despite his memory wipe to maintain secrecy. [[spoiler: It's actually GeneticMemory, he's a clone.]]
* After his transformation to Film/{{RoboCop|1987}}, what remains of Officer Murphy's mind experiences flashbacks of his prior life despite his memory being wiped.
* ''Film/{{Finding Nemo}}'': When Dory is swimming around the chain in the Sydney harbor, having lost grip on her memories again, she remembers almost nothing except that she "lost someone". She could either be referring to Nemo, who she has been watching Marlin frantically track down for the last few days, or [[spoiler: Marlin himself, who has just left her behind - the reason she's now lost and confused in the first place.]] The memories return when she hears the name "Sydney", which she has been repeating to herself the whole movie. A bit of a different example, since Dory has a fairly accurate case of real-life anterograde amnesia; her memories simply fell apart because she lost the social connection she associates with them. The Sydney address, another connection she has to her friend, repairs them.

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[[folder: Literature ]]

* In ''Literature/TheHeroesOfOlympus'', Percy's memories of the events in the [[Literature/PercyJacksonAndTheOlympians previous series]] are almost completely wiped at the beginning of ''Son of Neptune''. The "almost" is his memory of his girlfriend, Annabeth, though it's dim.
* Mind-wiping in ''Literature/ArtemisFowl'' leaves "residual memories" which can be used to trigger total recall.
* In ''Literature/{{Matched}}'' by Ally Condie, witnesses to an event are ordered to take a mind-wiping pill, but the main character only pretends to and keeps her memory.
* In Spindles End by ''RobinMcKinley'', the two main adult characters try to hide attention from their young ward (the princess) by altering the memories of the entire village such that everybody "remembers" her coming to live with them a month earlier than she did. It's an almost perfect spell... and when the person it missed figures it out, all heck very nearly breaks loose.
* In MelissaMarr's ''Graveminder'', Amity keeps a notebook to try to get around the town's magical amnesia. It is suggested, however, that she has trouble remembering to check the notebook.
* ''Literature/ChroniclesOfPrydain'' novel ''The High King''. Arawn Deathlord created the Cauldron-Born by putting dead bodies inside his Black Cauldron. They are mindless zombies completely under Arawn's control with no memories of their previous lives. When the defenses of Caer Dathyl were breached and the Cauldron-Born prepared to enter they saw King Math standing before them.
--> The deathless warriors of Annuvin halted as if at the faint stirring of some clouded memory. The moment passed and they strode on.

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[[folder: Live Action TV ]]

* Coincides with RippleEffectProofMemory in ''Series/TheFortyFourHundred''. The people who originally took the 4400 come back and [[spoiler: capture a large number of 4400 children, stating that the future has not been changed as they had hoped and that they must place these children into new parts of history so that they can alter the future.]] One of them, [[OracularUrchin Maya Skouris]] is wiped from all memory, with the exception of Agent Tom Baldwin, who continually sees her when his wife Alanna uses her powers on him. (She can psychically construct alternate realities for people.) He doesn't recognize Maya, but Alanna says that he must know who she is, since the alternate realities are created out of the subject's memories.
* This kicks off the main plot of the ''Series/StarTrekTheNextGeneration'' episode "Who Watches The Watchers"
* Twice on ''NoOrdinaryFamily'' with the same characters.
## Daphne uses her newfound [[JediMindTrick idea push]] powers to tell her inquisitive boyfriend not to ask about the family's special abilities. It works, but then a few hours later he broaches the topic again. So she pushes again, which works for a few hours again. Etc. She finally ends up telling him.
## Jim convinces Daphne to mind-wipe BF of his knowing about the family, so she gives him the instruction to "forget about when you learned I was special." This time it works too well, as he forgets their entire relationship.
* The memory drug in ''Series/{{Torchwood}}'', called 'RetCon', can sometimes leave nagging little details in the victim's mind. If they're distanced from all the weird things they've seen, it won't be a problem, but if something triggers it the memories come back. This is how Gwen re-learns of Torchwood in the pilot after Jack wipes her mind.
* Played with on ''Series/HouseOfAnubis'', When Fabian gets his amnesia curse. At first, he is still able to remember enough, like who Nina is, even though it does take a little work to trigger these memories. Though, eventually he does lose his entire memory, including his name.
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[[folder: Video Games ]]

* In ''VideoGame/{{Persona 3}}'', ordinary people who don't experience the Dark Hour have their memories revised afterwards to explain anything strange that occurs during the Dark Hour. (Which they might notice after it passes). In one scene, Mitsuru mentions that so many people are coming down with Apathy Syndrome that the memory revision can't keep up.
** At the end of the game, [[spoiler:either the protagonists (in the bad ending) or the ''entire world'' and the protagonists (in the good ending) have their experiences of the Dark Hour, as well as all the bonds of friendship and CharacterDevelopment that occurred because of it]], erased from their memories. Everyone, that is, except for [[spoiler:Aigis, who explicitly remembers everything]]. Depending on which ending it is, the character's situation is either wistful or downright FridgeHorror, because [[spoiler:in the bad ending she knows that TheEndOfTheWorldAsWeKnowIt is hours away from happening but there's absolutely nothing she can do to stop it, and she can't even tell her former friends about it because they don't even remember who she is]].
** It's also implied to have missed [[spoiler:to the Main Character in the good ending, since [=he/she=] can speak to Aigis about it in the last two days before graduation. However, since the narrative skips from the aftermath of the FinalBattle to the day before graduation, it's ambiguous whether [=he/she=] retained all memories along with Aigis and simply kept quiet about it for three months, or whether the memories came ''back'' on that specific day]].
** Also in ''VideoGame/{{Persona 2}}''. [[spoiler: At the end of ''Innocent Sin'', Philemon recreates the world at the catch that everyone will forget everything. Tatsuya Suou, The Hero of ''Innocent Sin'', keeps his memories out of sheer willpower, but is forced to give them up at the end of ''Eternal Punishment''. Big Bad Nyarlathotep, of course, remembers everything due to his supernatural status and restored the memories of the Ax Crazy Pyromaniac Tatsuya Sudou.]]
* The first ''VideoGame/KnightsOfTheOldRepublic'' had this as the backbone of the plot. [[spoiler: Revan's fragmented memories, as spied on through Bastila via the Force Bond]] were supposed to lead the Jedi to the Star Forge with your PlayerCharacter being none the wiser.
** Of course, in this case the amnesia might or might not have been accidental. Depending on which it was, the trope is either [[InvokedTrope invoked]] ([[spoiler: if the Jedi ''deliberately'' wiped your memories, the ''intention'' must have been for it to miss spots so that they could be used to find the Star Forge]]) or [[ExploitedTrope exploited]] ([[spoiler: if the amnesia was an accidental result of the circumstances of your capture, the Jedi took advantage of this at least as soon as they realized what was going on, and potentially as soon as they realized the ''possibility'' of this trope]]).

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[[folder: Web Comics]]
* In ''Webcomic/GenocideMan'' Joey reveals that his tweaked augments make him immune to the Lethe Protocol they use for discussions of things so terrible that plausible deniability isn't enough. [[spoiler: He takes advantage of that immunity to jog Jacob's memory of voting to use the [[SyntheticPlague Guyaquil Complex]] that killed a billion people.]]
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[[folder: Western Animation ]]

* In ''{{X-Men Evolution}}'', an entire sports stadium of people learn about the different mutants among them and their powers. To maintain their secret identities, Professor X tries to erase everyone's memory of the night, but blacks out before he can finish erasing Principal Kelly's mind. Principal Kelly later goes on to be very anti-mutant. The episode in question can be seen [[http://www.youtube.com/watch?v=jEN4uuENxfc&list=SL here]].
* In one episode of ''WesternAnimation/{{Futurama}}'' it looks like Fry was ground up into sausages and Leela goes to a memory erasure clinic to relieve the pain of his death. She is told before the procedure starts that it only hides memories, it doesn't remove them entirely and she might accidentally remember again. Meanwhile Fry is actually living among a Neanderthal tribe with blunt trauma-induced amnesia. Naturally, they both regain their memories upon meeting one another again.

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