• Director M. Night Shyamalan
• Writer M. Night Shyamalan
• Stars James McAvoy, Anya Taylor-Joy, Haley Lu Richardson, Jessica Sula, Betty Buckley
• Rating PG-13
• Running Time 1h 57m • Genres Horror, Thriller

At once solemn and preposterous, sinister and sentimental, efficient and overwrought, Split represents something of a return to form for its writer and director, M. Night Shyamalan. Or maybe I should say a return to formula. The movie, shot in and around Philadelphia, Mr. Shyamalan’s hometown, proceeds nimbly and with suave misdirection toward a pair of rug-pulling final twists that an attentive viewer will probably be able to anticipate. It’s not exactly a Choose Your Own Adventure, but you can opt either for the pleasure of surprise at the end or for the satisfaction of working out the puzzle as you go along.

Thanks to The Sixth Sense and Unbreakable back around the turn of the century, Mr. Shyamalan stands as a pioneer of spoiler-centric cinema. Like those movies, and like his later, lesser entertainments (The Village; The Happening), Split is all plot, an ingenious (and also ridiculous) conceit spun into an elegant ribbon of suspense. The less said about that plot, therefore, the better.

What I can safely divulge is that three teenage girls are kidnapped after a birthday party by a close-cropped guy named Dennis in a buttoned-up shirt. He is obsessed with cleanliness, and he sounds weirdly like John Turturro for a guy supposedly from Philly. In fact, Dennis is played by the soft-eyed, shapeshifting British actor James McAvoy, as are the other 23 personalities residing in the body of a guy who shares the surname of a famous (and famously odd) Philadelphia-born artist.

These “alters” — a word familiar to fans of the Showtime series United States of Tara and other pop-cultural treatments of a controversial and often poorly understood psychological disorder — are a diverse bunch. Some are male, some female, at least one is a child (named Hedwig) and another (named Barry) is a gay stereotype. What they want with their captives is not immediately clear. What Mr. Shyamalan wants is to strip them down to their underwear and to explore, exploit and occasionally subvert the basic tropes of the female-victim psycho-slasher movie.

One of the young women — a gothy, spooky misfit named Casey (Anya Taylor-Joy) — is singled out for special attention from the camera (though not, at least initially, from Dennis and his colleagues). Her fellow abductees, Claire (Haley Lu Richardson) and Marcia (Jessica Sula), alternate between panic and defiance, but Casey counsels patience and watchfulness. Flashbacks to a hunting trip she took as a 5-year-old (Izzie Leigh Coffey) in the company of her father (Sebastian Arcelus) and uncle (Brad William Henke) seem to explain the source of her survival skills, though it turns out that those memories have another, darker meaning as well.

Dennis and company, meanwhile — it’s mostly Barry, actually — consult with a therapist, Dr. Fletcher, who lives alone in a gracious, book-stuffed rowhouse and who is played by the wonderful Betty Buckley. Dr. Fletcher’s primary function is to explain the movie to the audience, foreshadowing the climax with her heterodox pseudo-scholarly theories about her many-sided patient, but Ms. Buckley also provides a dimension of warmth and wit that Split would be much duller and uglier without.