The dissociative identity disorder-suffering serial killer Kevin Wendell Crumb (James McAvoy, TV’s “Watership Down”) – also known as The Horde – is still at large in Philadelphia. With 24 distinct personalities, including the superpowerful Beast, the Horde’s actions are frightening in their unpredictability. Law enforcement officials are at a loss, but they’re not the only ones hunting.

For years, David Dunn (Bruce Willis, “Death Wish”) has been using his security system company as a base of operations from which to continue using his powers to fight crime. With the help of his now-grown son Joseph (Spencer Treat Clark, TV’s “Agents of S.H.I.E.L.D.”), David seeks out criminals as the shadowy vigilante the internet has dubbed “The Overseer.”

When David finds his way to the Horde’s hideout and releases the young women held prisoner there, he winds up face-to-face with the Beast. The battle between the two leads them out into the light, where they are confronted by a massive police presence and taken into custody.

They are sent to Raven Hill, a mental institution, where they’re place in the care of Dr. Ellie Staple (Sarah Paulson, “Bird Box”), a psychiatrist specializing in a delusional disorder that convinces the sufferer that they are a superhero. One of the other, long-term patients in this facility is none other than Elijah Price (Samuel L. Jackson, “Incredibles 2”), the self-styled supervillain dubbed Mr. Glass whose machinations led to the train crash that set David Dunn’s journey into motion.

At Raven Hill, Dr. Staple commits herself to figuring out how to convince these three men of their respective delusions, that their abilities, while impressive, are not superhuman in nature. In the course of her efforts, she deals with not just Joseph Dunn, but also Casey Cooke (Ana Taylor-Joy, “Thoroughbreds”) – the only person ever to be let loose by The Beast – and Elijah’s mother (Charlayne Woodard, TV’s “Pose”).

Meanwhile, Mr. Glass devotes himself to winning the trust of The Horde in hopes of enlisting the power of The Beast to escape custody. The only person with any hope of thwarting the machinations of Mr. Glass is David Dunn, but he has demons of his own that he must overcome. It’s all leading to a final showdown – one whose ultimate outcome is very much in doubt.

It’s easy to forget, what with his roller coaster from wunderkind to punchline to redemptive figure, that M. Night Shyamalan has some legitimate gifts as a filmmaker. Most of those gifts are evident in “Glass” – the creatively wonky aesthetic, the sharply coded color palette, the refusal to rush. His basic ideas remain compelling as hell and the characters that he’s wrapped in those ideas are equally engaging. Hell, he even folded in deleted scenes from “Unbreakable” as flashbacks.

Shyamalan’s flaws are here as well. He’s got a tendency toward clunkiness in his writing that’s tough to overlook. He struggles with narrative flow; the third act in particular leaves something to be desired. Some of the retconning necessary to make the pieces fit is clumsy at best.

And yet … I couldn’t help but be transported.

A lot of the credit for what works goes to the actors. McAvoy, who gave a tour de force performance in “Split,” is somehow even better this time. The eyeblink-quick shifts from personality to personality are incredible to watch; every one of the 24 is notably different thanks to his efforts. He’s shockingly good. And Jackson is just as good; he manages to be mesmerizing despite not even speaking for a significant chunk of his screen time. For a guy known for bombast, he can definitely underplay when he needs to. Willis brings up the rear through no fault of his own; he does well with what he has, but Shyamalan pretty clearly finds his bad guys more interesting. The rest of the ensemble – Paulson, Clark, Taylor-Joy, Woodard – gives us precisely what we need.

For reasons both good and not-so-good, “Glass” makes for a perfect conclusion to this trilogy. It’s an ideal encapsulation of this grounded super-aesthetic, a genre deconstruction that is somehow smarter than it’s given credit for while also not being as smart as it believes itself to be. All told, “Glass” is an uneven, yet ultimately satisfying ending.

[4 out of 5]