About halfway through this otherwise sleepy entertainment, Sarah Paulson, playing Philadelphia's best-dressed psychiatrist, gets to deliver an interesting piece of dialogue about the self-absorption of some superhero fans. She discusses the intensity of comic-book conventions.

This may explain why her patients believe themselves to be possessed of the powers that define Greek gods. Last summer,Paulson did indeed join co-stars Samuel L Jackson and Bruce Willis at the 2018 San Diego Comic-Con. Is a clever deconstruction of fandom afoot?

Not so much. M Night Shyamalan's sequel to Split and Unbreakable works hard at reassuring the less-balanced comics fans that their preferred art form really is as important as they believe. At the start of the century Shyamalan's excellent Unbreakable made an acceptable punchline of the notion that comics reveal hidden histories of the universe.

The super-beings really do walk among us. David Dunn (Willis), a man in a hood who avenges crime, is one such creature. Kevin Wendell Crumb (James McAvoy), the deranged loner who ate up Split, is another. Elijah Price (Jackson), a sly, damaged mastermind, is the most dangerous of the three. All are confined in a mental institution under the care of Dr Ellie Staple (Paulson).

Over the course of two long hours, Shyamalan – back on the downward swoop of his career sine wave – inadvertently demonstrates that the Unbreakable punchline cannot sustain even casual analysis.

Long before we’re told that, rather than watching a “special edition”, we’re experiencing “an origin story”, most casual viewers will have shuffled past the “vintage 1970s classics” and “collectable bobbleheads” in a desperate search for the exit.

Some effort and much expertise have gone into the production. Making up the characters – particularly the women – in bold, clean cosmetics, framing the action in neat compositions, the director convincingly replicates the look of a contemporary graphic novel.

If McAvoy tried any harder he’d risk bursting a blood vessel. The sensation, unfortunately, is of a less successful actor trying to get all his audition pieces on to the same reel. He does Irish. He does a woman. He does a child. He does a monster. “I can also fence to an acceptable level with sabre and foil,” he doesn’t quite tell the director.

The visible effort does not compensate for a story that rejoices in going nowhere interesting. The much-promised grand finale never arrives. The last reversal feels like a parody of the high Shyamalan style. He’s gone off again.

Opens January 18th