The Empire Strikes Back and The Godfather Part II are the famous exceptions. The structural reasons most sequels don't reach the original.
The film industry produces sequels because audiences buy tickets for them. The pre-sold familiarity of an existing IP reduces marketing risk; the audience that liked the first film is, in aggregate, more likely to show up to the second. By revenue per dollar spent on production, sequels are the most-reliable category in mainstream cinema.
By critical reception and durability, they are usually the worst. This essay tries to lay out why.
Almost every first film in a franchise is structured around a complete narrative arc. The protagonist starts in a state of stasis or limitation; an inciting incident disrupts the stasis; the protagonist responds; the response leads to escalating challenges; the protagonist either prevails or fails; the film closes with the protagonist in a new state.
This is the standard three-act structure. Almost every successful first film delivers it. When the film is good, the resolution feels earned and complete. The protagonist has changed; the world they inhabit has been altered.
The sequel has to start somewhere. The most-common choice is to reset some or all of the protagonist's first-film gains. The relationship that was established at the end of the first film has fractured by the start of the second. The skill the protagonist mastered has been forgotten. The new threat is structurally similar to the first threat but bigger. The protagonist relearns the same lessons.
This is the structural trap. The sequel's plot is, almost by necessity, a repetition of the first film's plot at higher stakes. Audiences feel the repetition even when they enjoy the surface entertainment. The third or fourth film in the franchise, by which point the repetition has become structural rather than novel, almost always disappoints.
The most-respected sequels in mainstream cinema are The Empire Strikes Back (1980) and The Godfather Part II (1974). Both films are structurally unusual.
Empire Strikes Back ends on the protagonists' defeat. Han is frozen in carbonite, Luke has lost his hand and learned that his father is the antagonist, the Rebels are in retreat. The film refused the first film's triumphal closure and instead deepened the audience's investment in the characters by giving them genuine losses. The structural lesson: the sequel can succeed by being morally darker than the first.
Godfather Part II uses parallel timelines — Michael Corleone in the 1950s intercut with his father Vito's rise in 1900s New York — to deepen rather than repeat the first film's material. The sequel's plot is not 'Michael fights a new antagonist'; it is 'Michael becomes what his father was, and the audience watches the parallel.' The structural lesson: the sequel can succeed by being formally more-ambitious than the first.
The other respected sequels — Aliens (1986), Terminator 2 (1991), Toy Story 2 and 3, the LOTR trilogy's later films, Mad Max: Fury Road (not strictly a sequel) — share at least one of these properties. They are either morally darker or formally more-ambitious than their predecessors.
The 2010s introduced a new sequel approach that the Marvel Cinematic Universe pioneered: the sequel as middle chapter of a planned multi-film arc. The first MCU films are not, strictly, standalone; they are setting up the Avengers ensemble films. The sequels are not, strictly, repetitions; they are continuations of an extended narrative whose structural unit is no longer the individual film but the multi-film arc.
This works for franchise management. It does not necessarily work for individual films. Many of the middle-period MCU films (the second Thor, the second Doctor Strange, the second Captain Marvel) are structurally compromised by their need to set up future material. The standalone film experience is sacrificed to the multi-film calculus.
The successful exceptions in the Marvel approach are the films that work as standalones first and as franchise material second. Avengers: Endgame (2019) works as a sequel partly because it is the structural payoff to a decade of setup; it earns its three-hour running time by closing arcs the audience has watched develop. Captain America: The Winter Soldier (2014) works because it is, primarily, a 1970s-style political thriller and only secondarily a franchise instalment.
The simple structural argument is: the sequel should be willing to actually do something to its protagonists rather than reset them. The protagonists at the end of the first film have earned changes; the sequel that reverses those changes for plot convenience is the most-common failure mode.
The other structural argument is: the sequel should commit to a formal ambition the first film did not have. Blade Runner 2049 (2017) is more-visually-ambitious than the original. The Dark Knight (2008) is more-structurally-complex than Batman Begins. The Wind Rises is more-mature than its director's earlier work. The films that take risks the first film did not are the films that survive as sequels.
The economics of mainstream cinema are not going to stop producing sequels. The franchise model is too commercially reliable. What will probably shift is the percentage of sequels that take real risks versus play it safe. The post-pandemic theatrical economy has, if anything, made the safe sequel more attractive — the studios cannot afford to risk a major flop on a $200m sequel, so the sequels they make tend to be structurally cautious.
The exceptions will continue to come from directors who can negotiate creative control. Denis Villeneuve on Dune. Christopher Nolan returning to the original concepts after each franchise instalment. Jordan Peele making thematically distinct films within his horror project. The structural argument for cinema's continued vitality remains the same: the directors are the variable that determines whether a sequel will be worth watching.