It is infuriating to watch a performance like James McAvoy’s in Split and know he will never get award recognition for it. A psychological horror, or any horror for that matter, rarely gets Oscar attention.  

But if only for his performance alone should people should go and see Split. The film tells the story of Kevin ‘Wendell’ Crumb (McAvoy), a man suffering from Dissociative Identity Disorder (D.I.D), or multiple personality disorder as it was previously called. Kevin has 23 different personalities.

One of those, ‘Dennis’, abducts three teenage girls and keeps them in an underground room for an unknown reason, not disclosed until the end. 

Friends Claire (Haley Lu Richardson) and Marcia (Jessica Sula) are taken with our main protagonist, social outcast Casey (Anya Taylor-Joy). Casey is a loner; something has happened to her, but we don't know what. On top of being terrified, the three girls are quite baffled by their strange capture.

We get to see three prominent personalities throughout; Patricia, a strict religious woman, Dennis, a severe sufferer of Obsessive Compulsive Disorder and Hedwig, a cute nine-year-old boy.

Kevin is also seeing a therapist, Dr Karen Fletcher (Betty Buckley), who strongly believes that the highly controversial disorder is real. In the sessions, she becomes increasingly worried that Kevin has done something terrible.

The appeal of Split lies in McAvoy’s enthralling and thoroughly believable performance. There is a scene when ‘Hedwig’ sneaks Casey to his room, urging her to be quiet in case anyone comes and it genuinely feels like someone could come into the room even though he is the only person down there with them.

Surreal humour is becoming a strength of Shyamalan's. The playful nature of some of the personalities juxtaposed with the horror of the situation is amazingly absurd. In the delightful moment the girls first encounter a different personality, ‘Patricia’ says with a knowing smirk: “Sorry about Dennis. He’s not well.”

Although Split is Shyamalan’s best effort since The Sixth Sense- after a few disastrous efforts- it still has some issues. Logic was never one of his strengths and that certainly doesn’t change here.

The film is a half an hour too long with moments of boredom frequently seeping in. The depth of Kevin’s character reveals the lack of effort gone into the others, except only more slightly for the troubled Casey.

Most problematically, Split is not scary. There is one jumpy moment which is over before you realise it’s happened. McAvoy’s character is more interesting and likeable than fearsome so the tension dissipates the more you see of Kevin.

By no means perfect, we can hope that Split may be a sign that Shyamalan is returning to his former heights. Split also joins the new generation of horror films that offer up an already capable female lead, which is exciting in itself.