M. Night Shyamalan has become somewhat of a joke. The writer/director, once renowned for creating masterpieces of tension and twists like “The Sixth Sense” and “Unbreakable”, spent the last decade churning out cinematic disaster after disaster. His 2015 effort “The Visit” was bad rather than horrible, prompting me to say he had ‘graduated from terrible to barely bearable.’

With his new “Split”, the upward trend continues, but this still isn’t a comeback. Shyamalan has graduated from barely bearable to mediocre.

The concept of “Split” is definitely inventive: a man with dissociative identity disorder kidnaps three teenage girls from a birthday party, leaving them to sort out his 23 personalities (of which we primarily just see four) in order to escape his mysterious plans. This idea is a minefield of potential: a nuanced, talented filmmaker could craft a gripping thriller or send an important message about mental disorders.

Unfortunately the filmmaker we get is M. Night Shyamalan, so instead there’s much talk about a supernatural 24th personality called ‘the beast’ and a message that should be offensive to anyone struggling with mental health or trauma. James McAvoy is really great as Kevin and his multiple personalities though.

While Shyamalan’s adequate skills as a visual artist have not dulled over the years — there are a number of clever shots that utilize a ‘split’ motif and the movie looks sufficiently grimy — his writing style reeks of the shameless bluntness that has plagued his last handful of films.

The dialogue and narrative of “Split” are hopelessly on the nose due to Shyamalan’s obsession with his signature twists. A maddening amount of lines and events hint at future plot surprises about as subtly as a Times Square billboard. There’s a session with Kevin’s psychiatrist early on which — if you’re paying more attention than someone sleeping through the movie — gives away the big twist, thoroughly explains how it’s logically possible, and flat out states one method to solve the conflict that the twist presents. Numerous flashbacks exist for little other reason than over-explanation.

Without giving anything away: the third act twist is so deeply bizarre that “Split” claws its way out of mediocrity by transforming into B-movie level insanity. It’s appreciably ridiculous, but the movie’s earlier clues are too obvious for it to come as a shock. Rarely are twists so simultaneously weird and predictable.

James McAvoy, not the plot, is the real star of “Split”. A role that is actually multiple roles requires range, and boy is McAvoy dynamic. He has long been a character actor in lead roles and “Split” showcases the height of this endeavor with unsettling energy. His nine-year-old boy personality is the most entertaining part of the movie, especially when dancing is involved. Anya Taylor-Joy is strong too, even if her performance consists of reacting to things.

The screenplay does their characters a great disservice though. The central idea that the film attempts to convey is that people who deal with mental disorders or personal trauma aren’t different in a bad way; they’re special in a good way. The piece of this message that “Split” unintentionally gets across is that their humanity has been altered, which could be insulting to many people.

Taylor-Joy is further objectified by the film’s uncomfortable appetite for young bodies. For a movie that has little to do thematically with sexuality, “Split” finds strange reasons to keep undressing its protagonists.

And to top it all off, if you stick around during the credits, you’ll be presented with a scene that is so preposterous that it’s either the boldest or dumbest move in the history of modern cinema. At least it’s more memorable than everything before the credits.

★★½ (2.5 out of 5)