A birthday party takes a nightmarish turn for friends Claire (Haley Lu Richardson) and Marcia (Jessica Sula) when they are kidnapped along with social outcast Casey (Anya Taylor-Joy). Waking in a dank basement, the terrified girls discover that their kidnapper, Kevin (James McAvoy), suffers from dissociative identity disorder (DID).

With each strange encounter, they must determine which of Kevin’s 23 personalities are out to harm them and which (if any) are trying to save them. And how can you escape when you never know who will be waiting just outside the door?

Written and directed by Shyamalan, Split takes the issues of mental health and abuse (psychological, physical and sexual) and adds a hint of the paranormal to create a strange viewing experience.

The story is told from three different perspectives: there’s Kevin, who shares his screen time with several of his other personalities; Casey, whose own dark past is revealed through a series of flashbacks, and Dr Fletcher (Betty Buckley), Kevin’s well-meaning psychiatrist who has some controversial theories about her patient’s numerous personalities.

McAvoy carries the film as Kevin; and his ability to switch effortlessly between personas is not just impressive, but at times downright eerie. Each has distinct characteristics and this, coupled with McAvoy’s strong performance, enables the audience to easily distinguish between the many characters sharing Kevin’s mind.

Although it has received criticism from mental health advocates for its portrayal of DID, Split is a darkly imaginative and engaging film. Shyamalan fans will expect a twist at the end … and there is one, but it may leave some viewers scratching their heads.

If you’ve already seen Split or don’t care about spoilers, you can read an in-depth article about Shyamalan’s latest twist here).