- Indiana Jones and the Temple of Doom starts out in typical Indy fashion, fast action, high adventure and a fun sense of humor. However, once you witness a man being sacrificed by the Thugee cult in a ritual involving tearing his heart out and slowly lowering into a pit of fire, the movie gets real bleak real fast.
- The Adam Sandler film Click starts off as a wacky comedy about a man who can pause and fast forward his life with a magical remote control. It eventually shifts from him making a hot blonde jogging go in slow motion to him fast forwarding through his life, becoming more and more of a jerkass, alienating his entire family, and influencing his son to become like him. He reaches his end when he suffers a major heart attack when his daughter calls his ex-wife's husband dad. He finally dies shortly afterwards after running into the parking lot of the hospital that he's at, after disconnecting himself from life-support, to beg his son to not become like him. Luckily for him, most of the movie is revealed to either be a dream, or Morty giving him a break..
- For much of its length The Great Waldo Pepper is a seemingly lightweight story about barnstorming pilots during the 1920s until a wing-walking attempt goes horribly wrong and the tragic incidents start piling up.
- The Harry Potter film franchise is relatively light-hearted until the end of Harry Potter and the Goblet of Fire when Voldemort is finally resurrected proper.
- Though this was arguably both foreseeable and intended, given the fact that JK Rowling wanted her readers to "grow" with the characters and the level of maturity of the books.
- Three Kings starts out as a madcap comedy/heist film until about a third of the way through, when we see a Republican Guardsmen execute a begging Iraqi civilian woman (in slow motion, no less).
- Pleasantville starts out on a pretty light-hearted note, until the darker aspects of the the movie version of 1950s start showing up. Both halves of the movie are very anti-Fifties, though, so if you're a fan of that decade the whole thing's arguably pretty dark.
- The Cable Guy. One of the reasons it failed at the box office was that fans of Jim Carrey were not prepared for how dark the film gets in the third act.
- Hancock starts off as a parody of the superhero genre, then devolves into a serious, straight superhero film during the second act.
- The Marrying Kind: What starts as a Comedy of Remarriage with a divorcing couple, becomes a serious look into a broken family after the midpoint.
- Marvel Cinematic Universe seem to be going towards this path. Justified in that the early movies were to introduce the characters and the universe that they life. So, as more films come, more the world is explored, and unsurprisingly, the movies grow darker from there.
- Compare the first Toy Story (a film about two unlikely pals bonding while escaping a Jerkass with an overactive imagination) to the third (a film about a group of friends escaping a totalitarian Crapsaccharine World, with part of the plot being arguably an adaptation of The Inferno).
- The first of the Pirates of the Caribbean films was a fairly light-hearted romp, especially in comparison to the sequels. By the third movie, Will is nearly killed off only to be saved at the cost of never setting foot on dry land (or being with his wife) again except for one day every ten years. Norrington also gets the axe and the series feels a lot more bittersweet than the first film alone might have suggested.
- Lord of War: The black comedy portions of the film end when Yuri decides to start doing business in Africa.
- Played straight in Juice. The film starts out as a coming of age tale about four late-teen boys and their city life experiences. Then Tupac Shakur gets access to a gun. Likes the thrill of having a gun. Things go bad very quickly.
- Oz: The Great and Powerful: Starts off as a whimsical fantasy romp. But then it delves into The origin of The Wicked Witch of the West and it becomes psychologically tragic.
- Underground: While the film begins with the bombing of Belgrade, the tone is lighter, mostly centering on Blacky and Marko's fight against the Nazis. As the focus turns more on the disastrous love triangle, the dissolution of Yugoslavia and the underground dwellers' confusion upon returning topside, the tones turns markedly more tragic.
Cerebus Syndrome / Film
Examples of movies or movie franchises getting progressively more serious.