[8] Bruce Willis, Samuel L. Jackson, Spencer Treat Clark, and Charlayne Woodard reprise their Unbreakable roles, while James McAvoy and Anya Taylor-Joy return as their Split characters,[9] with Sarah Paulson, Adam David Thompson, and Luke Kirby joining the cast.

The film sees David Dunn / The Overseer as he and Kevin Wendell Crumb / The Horde are captured and placed in a psychiatric facility with Elijah Price / Mr. Glass, where they contemplate the authenticity of their superhuman powers.

This necessitated securing the rights to use both Willis' and Jackson's Unbreakable characters from Disney, with the promise of including the studio in the film along with Universal Pictures.

Glass received mixed reviews from critics, who found the film "disappointing" and "underwhelming" due to the story, particularly the third act, but praised the performances of the cast; many deemed it the weakest in the trilogy.

David Dunn / The Overseer and his son Joseph track down Kevin, a man with multiple personalities called The Horde, to an abandoned factory near Philadelphia.

Mrs. Price (Elijah's mother), Joseph, and Casey Cooke (a victim who survived Kevin's captivity)[a] all try and fail to convince Ellie that superhumans are real.

He frees Kevin and then manipulates David into using his strength to break out of his room by relating a plan for The Beast to reveal himself to the world at the opening of the Osaka Tower, a new skyscraper in Philadelphia, while Elijah destroys a chemical lab in the building, potentially killing thousands.

However, when she overhears a group of comic book readers discussing the tropes of a super-genius mastermind, she realizes Elijah must have had a secret plan and discovers he arranged for the Raven Hill surveillance footage of the fight to be live-streamed to a private website, leaving her and her organization defeated.

Shannon Destiny Ryan, Diana Silvers, Nina Wisner, and Kyli Zion portrayed the kidnapped cheerleaders at the start of the film.

[15] In August 2001, he stated that, because of successful DVD sales, he had approached Touchstone Pictures about an Unbreakable sequel, but the studio originally declined because of the film's disappointing box office performance.

[16] In September 2008, Shyamalan and star Samuel L. Jackson, who played Elijah Price / Mr. Glass, stated discussions about making a sequel had been largely abandoned in light of the disappointing box office returns.

[18] Shyamalan worked on various unrelated films after Unbreakable before releasing Split (2016), which introduces the split-personality character Kevin Wendell Crumb / The Horde, played by James McAvoy.

Despite being preceded by hyper-realistic films about superheroes and villains, such as The Dark Knight (2008),[41] Shyamalan personally considered Glass to be the "first truly grounded comic book movie".

[42] On July 12, the first official photographs from production were released publicly, including shots of Samuel L. Jackson, Sarah Paulson, and James McAvoy.

[45] The first screenings of Glass occurred on January 12, 2019, at 25 Alamo Drafthouse Cinema locations, where it played during a triple-feature event that included and was preceded by Unbreakable and Split.

The website's critical consensus reads: "Glass displays a few glimmers of M. Night Shyamalan at his twisty world-building best, but ultimately disappoints as the conclusion to the writer-director's long-gestating trilogy.

[50] David Ehrlich of IndieWire gave the film a "C−" and called it the biggest disappointment of Shyamalan's career: "The trouble with Glass isn't that its creator sees his own reflection at every turn, or that he goes so far out of his way to contort the film into a clear parable for the many stages of his turbulent career; the trouble with Glass is that its mildly intriguing meta-textual narrative is so much richer and more compelling than the asinine story that Shyamalan tells on its surface.

"[58] Writing for Rolling Stone, David Fear gave the film three out of five stars: "Glass is not the flaming flop some folks have already suggested it is, nor is it the movie you want in terms of tying ambitious, highfalutin' notions together about how we process our pulp mythos.

[59] Owen Gleiberman of Variety wrote: "It's good to see Shyamalan back (to a degree) in form, to the extent that he's recovered his basic mojo as a yarn spinner.

Maybe that's because revisiting this material feels a touch opportunistic, and maybe it's because the deluge of comic-book movies that now threatens to engulf us on a daily basis has leeched what's left of the mystery out of comics.

"[60] Richard Roeper of the Chicago Sun-Times said the film had "a distinctive look and some pretty cool moments, and a half-decent twist or two" but that it was mostly "an underwhelming, half-baked, slightly sour, and even off-putting finale.

"[61] John DeFore of The Hollywood Reporter thought it was "a mixed bag" as a trilogy-closer, saying it does a good job of tying the narrative strands together, but that it tries too hard and fails to provide "something uniquely brainy" to the superhero genre.