Directed by M. Night Shyamalan

Starring James McAvoy, Bruce Willis, Samuel L. Jackson

When the serial killer thriller Split bowed on screens in January 2017, nobody knew that it was a back-door sequel to M. Night Shyamalan’s 2000 drama-masquerading-as-a-superhero-movie Unbreakable. It was a canny move on the polarizing filmmaker’s part; saving that twist until the last sequence allowed Split to stand on its own, and then giving it a final kick that let it soar into box office glory. But now the secret’s out, and Glass—the final entry in an envisioned trilogy—now has the unenviable task of uniting two films with divergent tones and different sensibilities into a cohesive whole. It doesn’t always succeed.

First, a recap of what’s gone before. In Unbreakable, an evil mastermind with brittle bones named Elijah Price (Samuel L. Jackson) orchestrates a massive train derailment that exposes unassuming security guard David Dunn (Bruce Willis) as a superman with superior strength and clairvoyant abilities. In Split, a murderer with dissociative identity disorder named Kevin Wendell Crumb (James McAvoy) kidnaps three girls, imprisoning them at an old zoo. He taunts them with 24 different personalities, culminating in two girls’ murders at the hands of a previously hidden, murderous personality called “The Beast”—a lethal entity with the superhuman abilities of the creatures at the zoo. Casey (Anya Taylor-Joy), one of the kidnapped, escapes, being spared because she was a victim of abuse like her captor.

Glass picks up a few years after the events of Split. David now runs a home security business. This is a cover for his true calling as a vigilante dubbed The Overseer who, at the beginning of the film, dispatches punks assaulting citizens for social media clicks. His real target is Kevin Wendell Crumb, who has now kidnapped four cheerleaders. Their confrontation lands them both in the same mental institution as Elijah Price. All three are now under the care of Dr. Ellie Staple (Sarah Paulson), a psychiatrist trying to convince them that their superpowers are delusions of grandeur.

From such a promising beginning, Glass disappointingly morphs into a pedantic therapy session. Shyamalan often shoots Sarah Paulson looking directly into the camera, waxing psychological about anything from her patients’ neuroses to Price’s “perspicacious mind” to the toxic culture of comic-book conventions. The inherent irony in Glass is that while it is painfully verbose, it’s also in a hurry to tick off plot points; one key moment has Dr. Staple engaging her presumably dangerous patients in a three-for-one session because of some random deadline.

The subculture of comics isn’t just a leitmotif running through Glass—it’s writ across the plot in giant letters, underlined three times with screeching chalk. Where Unbreakable slickly deconstructed superhero stories, speculating on how they would translate into real life, Glass takes the opposite tack: It takes its universe, supposedly rooted in realism, and tries to cram it into the narrative beats of a superhero story. At one point, a character with a new fascination for comic books has to have the idea of a “showdown” explained to her. At another, Elijah Price shouts with glee, “Ah, the classic turn!

Ultimately, Shyamalan is so intent on delivering on the promise of Glass’ two predecessors—even going so far as to integrate the title designs of Unbreakable and Split into the end credits—that he forgets to deliver a film compelling enough to stand on its own. And while a twist (the first of two!) explains why the climactic battle has to occur where it does, you can’t help but feel let down, as if you had been deprived of the spectacle and ingenuity you’ve come to expect as a moviegoer in the age of The Avengers. Sure, there are ideas to ponder—some interesting (superhero myths exist so we can recognize our own potential), some specious (sometimes the only way to escape a murderer is… be nice to him?)—but none of them land with any urgency. Glass cracks under the pressure of fan service, then shatters under the weight of its own unfulfilled ambitions.