For a director so renowned for twists and paradigm shifts, M. Night Shyamalan has seemingly saved the best one for his own career.

Back in 2013, I wrote a piece on directors I felt should call it a day and Shyamalan was near the top of the list. It was hardly difficult to argue at the time – Lady In The Water (2006), The Happening (2008) and The Last Airbender (2010) were all travesties, while the truly awful After Earth (2013) proved a new low.

This nadir proved something of a turning point as Shyamalan stripped everything back and returned to his low-budget roots by teaming up with micro-budget exploitation producer extraordinaire Jason Blum for 2015’s found footage flick The Visit.

The renewed promise of that movie is largely realised in this, their latest colaboration, which gifts James McAvoy the role of his career as Kevin, a man who exhibits 23 different personalities due to his being diagnosed with dissociative identity disorder (DID).

While the actual Kevin is largely an invisible bystander, three dominant personalities come to the fore – the threatening, uptight Dennis, the prim, manipulative Patricia and nine-year-old Hedwig.

This self-entitled ‘horde’ are compelled to abduct teens Casey (Anna Taylor-Joy), Claire (Haley Lu Richardson) and Marcia (Jessica Sula) for a purpose that becomes disturbingly clear as ‘Kevin”s visits to specialist psychologist Dr Fletcher (Betty Buckley) reveal a 24th personality known only as ‘the Beast’ is waiting in the wings to show himself.

Shyamalan has spoken in interviews of the opportunities a low-budget (approximately $10m) provides when it comes to taking risks. While the concept of split personalities is hardly original cinema (Hitchcock’s Psycho remains the high watermark), the film’s frightening opening scene of a kidnapping in broad daylight serves as a shot across the bows that all bets are off.

Tight close-ups are used throughout, focusing on McAvoy’s saucer-like eyes and trapping us in Kevin’s fractured psyche along with his trio of victims.

Aside from a completely unnecessary narrative device that leads to each of the girls being in a state of undress, Shyamalan places a brain in each of their heads and has them taking action to find a way out of their perilous dilemma.

As the outsider of the group, misfit Casey is naturally the smartest and tries to play one personality off against the other. A pretty pointless back story, told in flashback, endeavours to give Casey the agency she needs to survive, but Taylor-Joy (fresh from an equally affecting performance in The Witch) does more than enough with the material given to her to make these scenes nothing more than a distraction – towards the end especially.

While Taylor-Joy’s blood raw performance is excellent, it’s overshadowed by McAvoy giving it his all and then some in a dizzying turn. It’s the role of a lifetime for anyone brave enough to seize it with both hands and McAvoy unpacks what he brought to the table as a corrupt, mentally evaporating cop in 2013’s Filth and lets rip with a mesmeric barrage of verbal dexterity, contorted body language and unnerving unpredictability that somehow avoids falling into the pit of comical caricature.

The on-screen insanity masks some clunky dialogue, while it’s at least 20 minutes too long and, as a result, drags in places (there’s at least one too many visits to Dr Fletcher’s practice). Meanwhile, the very ending of the film will either make you smile at the director’s chutzpah or leave you wondering whether Shyamalan can ever truly leave the paradigm shifts on the shelf.

Nevertheless, Split is a B-movie treat for most of its running time – words you never thought you’d hear yourself say when describing another Shyamalan film.