A plot structure where the story starts off seemingly episodically, with apparently unrelated Monster of the Week assignments for the heroes to tackle as they establish themselves and their world. Then, either at the end of Act I or half-way through the story, The Reveal comes that a well-hidden Man Behind the Man has been putting those "unrelated" events in motion all along, and the rest of the story becomes dominated by the heroes struggle against this overarching villain.
Arc Welding is similar, but involves a Retcon of the originally genuinely standalone episodes into a new Myth Arc. Compare also Continuity Creep, where an episodic plot gains more and more continuity but not necessarily incorporates early episodes into it; and Connected All Along, which is about characters and their relationships (rather than plot events) being interconnected. Also see Innocuously Important Episode.
As a reveal trope, this one is Spoilered Rotten, so beware.
- In Kara no Kyoukai, most of the seemingly unrelated cases the Garan-no-dou agency investigates in the early episodes (as well as, to a lesser degree, Shiki's car accident) are revealed to have been the handiwork of the overarching villain, Araya Souren, half-way through the series. Even after Shiki kills him, two more chapters are devoted to cleaning up the mess left behind after his master plan was foiled.
- Madlax starts off with about eight episodes alternating between two seemingly unrelated main characters getting into seemingly unrelated predicaments. By the series' midpoint, it turns out that every early episode (even—nay, particularly—the Beach Episode) has set up specific plot points regarding the overarching myth arc.
- Fullmetal Alchemist starts off looking like it will be a road story about the Elric brothers visiting various Adventure Towns and Wacky Wayside Tribes while trying to restore Alphonse's body. Around the time of the first encounter with Scar, however, it becomes clear there's a much bigger plot afoot and that many of the previous misadventures were more important than they seemed.
- The early books in The Dresden Files were very episodic and none of the characters thought to ask whether the individual cases were connected, given how different in nature they were. Then, in Proven Guilty, they realized that a shadowy conspiracy they dubbed "the Black Council" must have been involved in all of them. Word of God is that the entire 20-volume arc has been planned from the start, so it was definitely intentional.
- Fringe starts off as a "Lighter and Softer X-Files" with a Monster of the Week format. The ongoing plot arc doesn't really get going until late in season 2—but after that, the writers have great fun referring back to the events of the early episodes (which can be done in creative ways as the arc involves Parallel Universes).
- Babylon 5, since it began before shows with arc-stories really took off, started with more or less self-contained episodic plots, especially in the first part of the first season, but a lot of them laid a foundation from which the later arc-heavy episodes would build on.
- Avadon starts off with your Player Party pursuing and dealing with several seemingly unrelated threats to the title fortress, before discovering a single guiding hand behind all of them and spending the rest of the game combating it.
- The first act of Dragon Age II consists of a bunch of disparate side quests that seem to be only connected by the "Hawke needs to make ends meet" thread. Come acts two and three, and nearly everything in act one turns out to be a setup for or a foreshadowing of the Qunari or the Mage-Templar storyline.
- Most Ace Attorney games are set up like this, with multiple self-contained murder cases ending up being linked through reveals in the final episode. The second game in the Investigations spinoff series is the best example though, as besides the killer of the first case being the victim of the second, the connections between each case are very subtle until the very end, leading them to feel like Monster of the Week plots at first. As a rundown:
- Case 1: The President of Zheng Fa? Actually a body double who killed the real one and took over. One of his bodyguards? The Big Bad's childhood friend, whom, unbeknownst to him, said Big Bad now hates, which is why he pushed him into murdering a fellow bodyguard. The totally-not-an-assassin ice cream salesman? Hired by the Big Bad to kill the fake president.
- Case 2: An ex-assassin inmate in the prison's high-security wing? The Big Bad's Parental Substitute due to the past event detailed in Case 5. The animal tamer at the circus? The game's Big Bad, and the one behind everything. The prison warden? Part of a conspiracy involving the fake president, which is why the Big Bad sets her up to murder Case 1's killer.
- Case 3: The victim from the past? Father of Case 1's killer, but the Big Bad mistakenly thinks he's his father. A witness from the past who appears, much older, in the present? The Big Bad's REAL father, and fleeing the country after committing a murder resulted in the Big Bad being put in an Orphanage of Fear, which led to him witnessing an assassination.
- Case 4: The senile old coroner? Involved in Manfred von Karma's evidence forgery. The head of the Prosecutorial Investigation Committee? Part of the evidence forgery coverup in Case 3, and also the third part of the fake president conspiracy, who murdered multiple witnesses to keep them quiet.
- Case 5: The Adorably Precocious Child? Biological son of the real president of Zheng Fa. This case's victim? The fake president from Case 1, here killed by the Big Bad. The SS-5 incident? The assassination of the real president of Zheng Fa, which took place at the orphanage the Big Bad was at, which was run by the warden from Case 2. The Big Bad witnessed the president's murder as a child, and saved the hired assassin when the conspirators planned to go Contract on the Hitman. This led to his extreme misanthropy, and his elaborate plot to make the three conspirators lives' hell by any means necessary. Phew.
- Steven Universe starts off with the simple, goofy one-episode conflicts typical of children's shows, but steadily drops hints about the Crystal Gems' backstory and the nature of their kind. Then at the end of the first season it's revealed that there are other gems who have sinister plots regarding the Earth. Now there's rarely an episode that doesn't contribute in some way to the Homeworld Gems storyline or someone's Character Development/Hidden Depths, though there are still a few.
- Transformers: Prime had a couple of episodes in the first season where they find artifacts that originated from Cybertron. They seemed like isolated incidences, with some of the artifacts destroyed by the end. But the second season reveals these artifacts were sent to Earth as part of a long term plan by Alpha Trion, which ties in directly with the Myth Arc of the season.
- The first season of Wander over Yonder is all light-hearted one-off stories. Season two introduces Lord Dominator, and each episode deals with her threat in some way or another. Even in episodes when she doesn't appear, she is mentioned at least once as someone that needs to be dealt with.