Samuel L. Jackson plays the role of “Mr. Glass” Elijah Price, the supervillain in M. Night Shyamalan's film called “Glass.”

Samuel L. Jackson’s Elijah Price, or Mr. Glass as he prefers to be called, was the most compelling part of M. Night Shyamalan’s former slow-burn comic book send-up “Unbreakable.” A brilliant, tortured manipulator suffering from brittle bone disease, Glass is that kind of charismatic supervillain that you can’t get enough of.

Nineteen years is certainly a long time to wait for more Mr. Glass. But Shyamalan decides to withhold him from the audience even longer: Mr. Glass is a highly sedated vegetable who does little more than blink and intensely stare for what feels like more than half of the movie.

It’s one of the many ways in which the film, which seems to delight in building up anticipation only to pull the rug out from under you, manages to both frustrate and underwhelm.

I’m sure it’s some kind of meta-commentary on the futility of serialized storytelling, the contrivances and deification of comic book culture and easily malleable audience expectations, but in execution it mostly feels like half-baked ideas that never really coalesce into something exciting, meaningful or all that memorable.

“Glass” definitely doesn’t care to help if you haven’t seen “Unbreakable” or “Split,” either. It just dives right in with little exposition. We see Bruce Willis’s David Dunn taking a couple of teen pranksters to task. Then it jumps to James McAvoy’s multiple personalities, who’ve decided to take four teenage cheerleaders hostage because they’re “impure” and “need to be punished.”

David, who is working alongside his now-grown son Joseph (Spencer Treat Clark, the same actor from “Unbreakable,” which is actually a nice touch), has been trying to find the missing cheerleaders. Joseph warns him to be careful, because David has also been branded a public nuisance for all of his would-be good deeds that have left criminals and victims injured and looking for someone to sue. If you’re thinking this is the plot of “Incredibles,” just wait because it brushes up against “Incredibles 2,” intentionally or not.

David and the “Horde” (the term used to describe the collective of all of McAvoy’s personalities, which range from a 9-year-old boy and an older British woman, to a terrifying flesh-eating creature called “The Beast”) meet and low-budget fight a bit, but are interrupted by the authorities and Sarah Paulson’s Dr. Ellie Staple who take them to the psychiatric hospital where Price is.

This little group therapy session is one of the more compelling parts, and it seems like the film is gleefully destroying the superhero origin story myth, sending its main characters into a spiral of doubt.

But don’t get too attached to this, because Shyamalan will change course, backtrack and laugh at you for getting too committed.

Mr. Glass does emerge from his vegetative state, eventually, and kicks the movie into gear. McAvoy is once again giving his all to all the characters. Willis barely gets anything to do at all. But for all the hype behind these three characters meeting, and the years it took to get it off the ground, “Glass” is one big anti-climax.