Going into a M. Night Shyamalan film nowadays comes with certain guarantees. You’ll have been wooed by the trailer, believing he’s back on The Sixth Sense sort of form. After an hour, you’ll feel the eerie creep of disappointment settling in. By the end, the “twist” will lead to abject dismay and a vow never to trust him again. But then he serves up James McAvoy playing a man with twenty-three distinct personalities.

So, we all jump aboard the Shyamalan train once again. This time we know from the adverts that McAvoy’s character kidnaps three teenage girls. They come in the guise of Skins’ Jessica Sula and her best buddy, Haley Lu Richardson’s Claire. When they’re nabbed, they are leaving Claire’s birthday party and have sympathy invite – and our lead protagonist – Anya Taylor-Joy’s Casey with them.

So far, so good. The build begins for a psychological thriller. We first meet Dennis, an OCD strict jailer. This personality is kept in check by Patricia, his female personality that helps run the gig. The plan is to feed the girls to The Beast, a yet-to-be-met personality that is above all humankind.

Do you feel that thriller swinging toward a horror?

In between captive scenes, we see Dennis parade as Barry to his therapist and seeks counsel. She totally buys the idea that within a person, multiple, completely separate identities can exist. She even gives examples how physiological changes occur depending on the personality assumed.

The host in this case is Kevin but he’s been overrun by Dennis and Patricia. The collective is known as The Horde. It’s explained they all sit around a circle waiting for their time in the light. Kevin’s nine-year-old personality, Hedwig, has the ability to control people’s slot in the light. He’s agreed to assist Dennis and Patricia because they prevent The Horde poking fun at him.

For a time, it becomes teen slasher. The girls try revolts and get put into solitary confinement. But throughout all the main actors do their roles justice. McAvoy is impressive carrying the load of diverse personas but it’s no Heath Ledger as The Joker. More, engaging performance amidst a struggling script.

When we finally get to meet The Beast, the movie becomes ludicrous. It’s okay to suspend disbelief if the requirement is made clear early on. But to start with a grounded tone, have scenes stressing the seriousness of dissociative identity disorder, to then descend into something that would look ridiculous in a modern-day comic book is almost unforgivable.

4/10 . . . if the film finished a few minutes earlier than it did.

Remember how M. Night Shyamalan likes to throw in a twist? Well, he does it again here. I’ll not ruin it for you but that “almost” before unforgivable is for occasions such as this. For the sake of a quick shock in the cinema, he would have been better just laying his cards out in advance. Doing so would have enhanced the viewing of the movie rather than numerous headshakes at the screen and the laughter it unintentionally provided in various scenes.

5/10 (Probably should be more after the final scene sinks in but M. Night Shyamalan has missed a trick.)