“Who are we?” wonders Jean Grey – the telepathic, telekinetic, soul-searching heroine of Dark Phoenix – in the film’s opening voiceover. Any telepath around could have looked into her mind and answered: “Well, you’re not someone interesting.” This latest instalment in the X-Men franchise is flatter than a wafer-thin page of the comic books that inspired it. The film is done in by a drab script and a surprisingly dull Sophie Turner, whose performance as Jean, aka Phoenix, supposedly in emotional turbulence as she sorts out whether to use her powers for good or evil, has none of the wiliness and depth Turner displayed as Sansa Stark on Game of Thrones.

Dark Phoenix is especially disappointing because the X-Men series has always been the smartest, most sophisticated of today’s action-hero movies. That difference is largely thanks to James McAvoy’s cerebral Professor Charles Xavier, whose mind-control abilities make mental powers seem dynamic, and Michael Fassbender’s Erik Lehnsherr, who becomes Magneto. His haunted past drives his thoughts, and his ability to move giant chunks of metal.

Charles and Magneto are in Dark Phoenix, along with other familiar characters. They include Jennifer Lawrence as the shape-shifting Raven, who tries to be a mentor to Jean. Nicholas Hoult is Hank or the Beast – sometimes looking human, sometimes blue and hairy. Tye Sheridan is Jean’s boyfriend, Scott, who can shoot powerful beams out of his eyes. But these characters seem to walk through the script, without the visceral connections that have made them a team – often split by rivalry – in the past.

It’s surprising that such a promising, character-driven premise never takes off

The story arc is so straightforward it’s hardly an arc at all. After a quick flashback to a trauma in Jean’s girlhood, which led her to Xavier’s school for powerful mutants (as it should properly be called), the plot picks up in 1992, a decade after the events of X-Men Apocalypse. The X-Men are launched into space to save a damaged US space shuttle, and while the mission succeeds there’s a nasty side effect. Jean absorbs solar flares that enhance her dark energy, making her the most powerful of mutants. For the rest of the film she struggles with how ‘good Jean’ can prevent ‘bad Jean’ from taking control and killing people.

In an early scene, evil Jean tosses police cars in the air, smashes houses and kills a beloved major character – at least for now. Who really stays dead in action-hero sagas? Their landscapes are now littered with more formerly-dead characters than most zombie movies. The X-Men, ever philosophical, are split between wanting to save Jean from herself, or destroy her for the good of the world.

It’s surprising that such a promising, character-driven premise never takes off, because the film was directed and written by Simon Kinberg, who has had a role producing or writing the X-Men films since The Last Stand in 2006. As a director, he lacks a flair for working with actors. Jessica Chastain is wasted in her role as an alien named Vuk who takes over the body of a human and befriends Jean, planning to use her powers to allow the aliens to take over the Earth. With an impassive expression throughout, Vuk never seems persuasive or dangerous.

Kinberg does comes through with a couple of spectacular action scenes. Jean seeks out Magneto on an island where he and other mutants have found peace. (Fingers crossed for a reality series, Survivor: Mutant Island.) When military helicopters arrive to take Jean away, Magneto puts up his hands and fends them off. It seems that Fassbender can do anything, because he actually lets us see and believe in Magneto’s physical and emotional struggle in that scene.

A bigger battle takes place in New York City, where Magneto, Charles and the other X-Men have tracked down Jean and Vuk. Magneto’s powers lift a subway train up out of the ground and send it hurtling into the front hall of a luxurious building across from Central Park. But two good action set pieces aren’t enough to keep things lively.

It’s hard to be engaged when the characters themselves seem so detached

The screen glows with fireballs of energy every 10 minutes or so, but the better special effects are imposed on Jean’s face. When her dark powers emerge, tiny lightning-like bolts appear on her face, as if it were being cracked by golden veins. Her eyes turn gold and glowing. It’s a creepy, effective image. At least Jean looks sinister, even if Turner gives her nothing behind that mask.

Dark Phoenix brings in the themes that most action-hero movies rely on. There’s the question of how to use superhuman powers, balanced by the humanising conceit of the heroic team as a family. Will the family hold or break apart? Earlier, better X-Men films, notably First Class (2011), allowed audiences to feel invested in these issues and the outcome. Here, it’s hard to be engaged when the characters themselves seem so detached.

Kinberg’s script has the occasional flash of wit and meta-awareness of the franchise’s history. When Magneto meets Charles again, his old friend and rival begins to explain why they should save Jean instead of killing her. Magneto says: “There’s always a speech.”

And Raven snaps at Charles, “By the way, the women are always saving the men around here. You might consider changing the name to X-Women.” The line is calculated to please audiences, but it’s hollow. Phoenix goes through the uninspired motions of saving the world, but she can’t even save her own film.

★★☆☆☆

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