A plot arc that was incomplete and forgotten, and then suddenly brought back out of the blue to continue the plot arc itself. This is distinct from the ContinuityCavalcade and ContinuityPorn tropes in that it's not just a ShoutOut type situation - the plot arc is resumed, essentially where it left off.

In short, what distinguishes PlotArchaeology from similar tropes is that it's not just a one-episode reappearance, either as a ShoutOut or a full-fledged SequelEpisode (which may be considered a SubTrope). Do not confuse with [[AdventurerArchaeologist an archaeology plot.]]


[[folder: Comic Books ]]
* ''Franchise/SpiderMan''
** The true identity of the Hobgoblin. The villain first appeared in 1983; his true identity, fashion mogul Roderick Kingsley, had first shown up three years prior. His creator Roger Stern planted a number of {{Red Herring}}s but maintains- and is corroborated by other writers- that he intended Kingsley to be the Hobgoblin all along and to reveal him after a couple of years, taking advantage of the fact that Roderick had a servile identical twin that Stern managed to sneak in without being noticed. The problem? Stern was fired not even halfway through the MythArc, and subsequent writers either disliked the Kingsley idea or didn't know about it. Doesn't help that at least two characters were framed as him- Flash Thompson, and a thug named Lefty Donovan, before Ned Leeds was KilledOffForReal and then, in an AssPull, "revealed" as the "true" Hobgoblin all along because the writers had gotten tired of the mystery and decided to introduce a ''second'' Hobgoblin, mercenary Jason Macendale (hitherto a minor villain known with the alias Jack O'Lantern), who quickly and unintentionally became a BigBadWannabe. It wasn't until 1997 that Stern was invited back and allowed to wrap up the story as he originally intended it- quite remarkably, the Kingsley idea was still internally consistent to the story and caused no real plot holes (if you pay attention, at least). For the whole story in ''painstaking'' detail, [[http://www.spideykicksbutt.com/SquanderedLegacy/SquanderedLegacyTitle.html check out these essays.]]
** ''ComicBook/TheCloneSaga'' revisits the "original clone saga" story arcs from ''Amazing Spider-Man'' #121-149.
** ''ComicBook/OneMoreDay'' and ''ComicBook/OneMomentInTime'' revisit "The Wedding!" from ''The Amazing Spider-Man Annual'' #21.
* ''Comicbook/XMen''
** Comicbook/{{Cable}}'s introduction in ''ComicBook/NewMutants'' was based on the baby Christopher appearing in ''Comicbook/UncannyXMen'' #201, from four years earlier.
** Mystique reveals her true form to Nightcrawler, who is shocked that they look very similar. She mentions his mother's name. ''10 YEARS'' (or more) later, it's revealed that she is his mother. It hadn't been even mentioned in the comics in-between those two points.
** The Third Summers Brother. In 1993, Mr Sinister casually refer to Cyclops having "brothers", then corrects himself. This arc got aborted when Fabian Nicieza left the X-titles before he could reveal the third brother was Adam-X, the X-Treme. Over the next ten years, the concept was never referred to. (Robert Weinberg thought it was Apocalypse, but also left the book before he could say so). In 2004 Creator/ChrisClaremont suddenly brought it up again, and revealed it was Gambit, but that was in an AlternateContinuity. Then, in 2006, Scott and Alex finally meet Gabriel Summers, aka Vulcan. Unfortunately, Vulcan's backstory makes it impossible that Sinister could have known about him in order to make that casual offhand reference. Fans now wonder if there's a fourth Summers brother. Or perhaps even more than that; Sinister didn't mention a number, just that Cyclops has more than just the one brother he was aware of at the time.
** Following ''ComicBook/AgeOfApocalypse'', the ''Mutant Massacre'' storyline was revisited, with Dark Beast and Gambit being {{Retcon}}ned as having participated in the event.
** In ''ComicBook/{{Onslaught}}'', the X-men use technology to remotely view the moment when Onslaught was created, when Professor Xavier attacked Magneto during ''Fatal Attractions''. Onslaught is also revealed as the cause of the X-traitor message that motivated Bishop to travel to the past.
** ''The Twelve'' revisits ''The Twelve'' storyline introduced in ''ComicBook/XFactor'', though changing the roster of twelve mutants.

[[folder: Film ]]

* ''Film/StarTrekIITheWrathOfKhan'' was all about digging up a one-episode villain from the first season of the original series and answering Kirk's question about what would happen with the "seed" that the Enterprise crew planted.


[[folder: Literature ]]

* In the ''Literature/AnitaBlake'' series, the events of book 11 resulted in the vampire serial killing group Anita was after not actually getting caught. Fans bitched and complained when the next few books didn't mention it at all, and then in Book 17 LKH went back to it and we finally get to confront the BigBad. A few other loose threads from that were also left hanging in that book and the one right after it which are still waiting to be picked back up though.
* ''Toys/{{Bionicle}} Adventures #10: Time Trap'', from the end of 2005 revisits several issues that were left hanging in '04, six books earlier, such as the recovery of the lost Mask of Time and the Shadowed One's reaction to the deaths of two of his servants at the hands of Makuta. The Mask of Time plot was briefly continued in an online serial three years later.


[[folder: Live Action TV ]]

* In the first season of ''Series/{{Heroes}}'', Hiro falls in love with a waitress named Charlie. It turns out she has a brain tumor and is going to die. Hiro [[spoiler:accepts that he can't save her, gets some CharacterDevelopment, and the plot moves on. Several seasons later, Hiro regrets that he didn't save her, and the arc focuses on her again as Hiro goes back in time to try and save her, but she gets kidnapped and held hostage by the BigBad.]]
* ''Series/NewsRadio'' had a storyline where Lisa decided she wanted to have a baby with Dave. This went on for a few episodes, then was quietly dropped. In a later episode the same season, there is a brief conversation about how the moment had passed. The writers hated continuing story lines, which the network continually tried to force on the show.
* The First Evil from ''Series/BuffyTheVampireSlayer'' makes a one-off appearance in season 3. It shows up four seasons later as the BigBad. A script involving the First that they didn't use for Season 5 became the basis of one of the Xbox games.
* ''Series/StargateAtlantis'': Stardrives were mentioned very briefly in an early episode and didn't become massively important until the finale three seasons later.
* ''Series/DoctorWho'':
** The Third Doctor casually mentions Metebelis III in a throwaway line at the beginning of "Carnival of Monsters". In the last story of Season 10, he takes a quick and mostly comical trip to Metebelis III while sulking about Jo's departure, which mostly serves the purpose of giving him GreenRocks to use as a deus ex machina. The final story of Season 11 is set partially on Metebelis III, and it turns out the planet is extremely important in his eventual downfall.
** ArcWords sometimes get planted before they're even used in a this-is-leading-up-to-something fashion. We get a briefly-seen newspaper mention of "Saxon" being ahead in the polls midway through new series Series 2. Nothing is said of it until "Mister Saxon" becomes a mystery figure of Series 3.
** River Song was introduced in "Silence of the Library" and quickly dropped, then brought back with the Eleventh Doctor.
** There's a gag mentioned in the Season 4 Specials that Queen Elizabeth I, due to getting involved with the Doctor in some fashion, is "no longer known as the...''...''". This plot thread is used prominently in big chunks of "Day of the Doctor", which details this involvement.
** "Into the Dalek" deals with dropped plot points introduced in "Genesis of the Daleks", a Fourth Doctor story made way back in 1975.
* In ''Series/StarTrekTheNextGeneration'', Wesley Crusher is built up as being a very special person, and it is suggested that he would do something remarkable, eventually. Then he was phased out of the show, and was gone for something like three seasons. Come the final season, the CreatorsPet returns, and the plot arc completes itself.
* At one point, ''Series/UglyBetty'' had a plot arc about Amanda trying to discover the identity of her biological father. After a few episode, the plot disappeared with no resolution. In the show's GrandFinale, Amanda finds her father, out of the blue and completely by accident.
* In ''Series/{{Sliders}},'' the Kromaggs were a season two MonsterOfTheWeek who got one mention in season three. Then comes a ChannelHop... and their return as the franchise BigBad.
* On ''Series/TheWire'', [=McNulty's=] FBI buddy gives him the results of an unfinished investigation that showed Lt. Daniels was dirty when he was on the Narcotics task force. [=McNulty=] doesn't trust him for most of the first season, but eventually the men grow to respect each other. This is not mentioned again until the series finale, when now-Commissioner Daniels is forced to resign rather than be manipulated by the threat of revealing that very same investigation.
* On ''Series/BabylonFive'', much of Captain Sheridan's character arc in Season 2 centers on [[DeathByOriginStory the death of his wife]] and how he needs to let it go and move on with his life. Fast forward to the end of Season 3, and [[spoiler: Anna Sheridan shows up on B5, with a message for her husband from the Shadows.]]


[[folder: Manga & Anime ]]

* In ''{{LightNovel/Durarara}}'', the slasher is mentioned early on a couple times but not addressed until much later.
%%* In ''Manga/{{Bleach}}'', a number of plots are left unfinished in the wake of newer developments, only to be brought up much later in the story.


[[folder: Video Games ]]

* Quite a few minor plots in the earlier ''Franchise/MassEffect'' games come back in ''VideoGame/MassEffect3'', sometimes in unexpected ways. An entire {{DLC}} of the third game, with profound revelations about the entire setting, is a CallBack to a throwaway bit of WorldBuilding fluff text in the first game. A villain from one of the first game's [=DLCs=] can end up being recruited as an ally in the third game, and so on.
* Many of the subplots of [[{{VideoGame/WorldOfWarcraft}} World of Warcraft: Legion]] are conclusions to plot threads dropped long ago.
** Perhaps the most notable is the return of Alleria and Turalyon. They were part of the Alliance Expedition that disappeared at the conclusion of Warcraft II. Most of the members were found during the Burning Crusade expansion of World of Warcraft, but Alleria and Turalyon were still missing. After 20 years in real life (just a few years short of the in-universe time that they were missing), their whereabouts are finally known, and where they had disappeared to forms a crucial part of the main plot.
** Another longstanding one was the fate of Calia Menethil, the sister of Warcraft III's Arthas. She was mentioned in a novel that took place before Warcraft III and the massacre of her family and kingdom, but she was scarcely mentioned anywhere else, so her fate was uncertain. Speculation on her fate abounded, but official sources tended to ignore her altogether. In Legion, she finally returns, having escaped the fate that befell most of her kingdom.


[[folder: Western Animation ]]

* ''WesternAnimation/AvatarTheLastAirbender'': one early episode introduces Bato from Katara and Sokka's father Hakoda's fleet, and suggests the kids can meet up with the fleet. When this fails, no further attempts are made to meet up with Hakoda or the fleet until the end of the second season.
* At one point in ''WesternAnimation/SupermanTheAnimatedSeries,'' ComicBook/{{Brainiac}} blasts former partner ComicBook/LexLuthor with a ray that (like many instances of FamilyFriendlyFirearms) doesn't seem to hurt him much for what appeared to be intended as a killshot. Much much much later in ''WesternAnimation/JusticeLeagueUnlimited,'' we find that [[spoiler: ''that's because it actually wasn't.'' Brainy put his data inside Lex in case he was destroyed, and this backup of himself was now needed. Enter... [[FanNickname Brainithor!]]]] ThePowersThatBe have said that they'd actually planned it the day they wrote the zapping scene, they just didn't have the right opportunity to use it for a long, long time. Lucky for them the DCAU lasted long enough to do it.
* In ''WesternAnimation/TransformersAnimated,'' Porter C. Powell makes a single not-terribly-memorable appearance in the first season and it doesn't look like he's intended to return. In season two, he does... with a vengeance.
* Unicron in ''WesternAnimation/TransformersPrime'' first appears and is dealt with at the end of season 1. After being mostly forgotten for the following two seasons, he reappears to follow up on his plans in the series finale movie ''Predacons Rising''.