“The Dark Phoenix Saga” played out over the course of almost 40 issues and four years of Uncanny X-Men comics. It began slowly, with mutant hero Jean Grey seemingly sacrificing her life to save her fellow X-Men during a space mission gone wrong, only for Jean to be magically reborn as the almighty Phoenix. In writer Chris Claremont and artists Dave Cockrum and John Byrne’s “Dark Phoenix” Jean’s transformation from heroic X-Man to out-of-control demigod takes dozens of issues to unfold. Readers watch her slowly succumb to the corrupting influence of the incredible power she possesses, and observe how her evolution affects each of the other X-Men. “The Dark Phoenix Saga” is one of the greatest comics story in large part because it could only be told in comics — serialized with methodical, intricate plotting that gradually builds to an epic, tragic crescendo.

Dark Phoenix is the second attempt (after 2006’s X-Men: The Last Stand) to try to cram those 40 issues and four years of comics into a 110-minute movie. The films have failed in different ways and to varying degrees, although somewhat surprisingly, one man was partly responsible for both: Simon Kinberg, who co-wrote The Last Stand and wrote, directed, and co-produced Dark Phoenix. His new version of this story is more faithful to the comics than his first one, but the problems with The Last Stand (which was directed by Brett Ratner) always had less to do with fidelity than the size of the canvas the creators’ had to work with.

That’s been something of a bug of all of these X-Men prequels, starting with 2011’s X-Men: First Class, which was set in 1962. Each subsequent movie has been set roughly a decade after the last, up to and including Dark Phoenix, which takes place in 1992. That means even though James McAvoy and Michael Fassbender are still handsome young men, their characters — telepathic Professor X and master of magnetism Magneto — are now technically in their 60s. Even more distractingly, each time we rejoin the characters ten years after their last adventure, their behaviors and motivations have shifted wildly. These movie X-Men are only uncanny in their inconsistency.

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In Dark Phoenix, the most drastically different is McAvoy’s Xavier, who relishes what’s become of his X-Men in the decade since the events of the last movie, X-Men: Apocalypse. His former students — shape-changing Mystique (Jennifer Lawrence), ferocious Beast (Nicholas Hoult), laser-eyed Cyclops (Tye Sheridan), telekinetic Jean Grey (Sophie Turner), teleporting Nightcrawler (Kodi Smit-McPhee), weather-controlling Storm (Alexandra Shipp) and guy-who-runs-fast Quicksilver (Evan Peters) — are now famous, beloved superheroes. Xavier has a Bat-Phone that goes directly to the President of the United States. The formerly selfless mutant leader has let the adulation that comes with success go to his bald head, and he keeps encouraging the X-Men to take greater risks, despite the objections of Mystique.

Xavier’s arrogance comes back to haunt him after a rescue mission in space goes wrong and Jean comes into contact with a strange cosmic entity. At first, it only seems to enhance her powers. But then this Phoenix amplifies Jean’s natural gifts beyond her control — and exposes secrets from her past that had been deliberately buried decades earlier. All of that emotional turmoil sends Jean into a tailspin, and she becomes increasingly dangerous, until the rest of the X-Men need to decide whether to help their friend or destroy her.

They also need to contend with the mysterious character played by Jessica Chastain, who serves as the devil on Jean’s shoulder, urging her to destroy her colleagues and embrace her destiny as the most powerful creature on the planet. I won’t spoil who Chastain is playing, or her reasons for manipulating Jean, but I will say that of all the Marvel characters she could be, the one Kinberg chose is a bit of a letdown.

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While Chastain adds little to the ensemble with her distant, impassive line readings, the returning cast remains among the most overqualified in summer blockbuster history. Michael Fassbender is far too talented to have squandered almost a decade playing Magneto, but he gives the role every ounce of intensity he can muster, even when the material doesn’t deserve it (like in Dark Phoenix, where his role is frustratingly minor). McAvoy brings some new shades to the egotistical Xavier, until the movie basically forgets that’s supposed to be his character arc and abandons those changes completely during the formulaic third act.

Kinberg, who’s a writer and producer by trade, makes an adequate but unexceptional first-time feature director. Even in the cruddiest X-Men movies, there’s usually at least one or two fun sequences where the mutants show off their powers. Dark Phoenix really doesn’t have one until the very end, a prolonged action sequence on a train where the various characters get to use their abilities against a bunch of bad guys. It’s a solid bit of comic-book business, but for a movie about a space deity who threatens to engulf the entire globe in magical fire opening in theaters on the heels of maybe the biggest superhero movie of all time, it feels awfully small.

That’s true of a lot of Dark Phoenix. It’s very hard to tell this story in a satisfying way in this little amount of time. Multiple characters undergo life-altering changes of perspective — flipping from good to evil, sympathetic to monstrous — in a matter of seconds. The whole movie hinges on Jean Grey, a character we hardly know (the Sophie Turner version was introduced in a minor role in X-Men: Apocalypse) and her relationships to a team of heroes we’ve hardly seen. The film is like an adaptation of the original Dark Phoenix comics, and also of the Anchorman “Well, that escalated quickly” meme. Everything happens too fast, until the whole structure goes down in flames.

Additional Thoughts:

-Unbelievable but true: Jennifer Lawrence has now spent more than twice as long in the X-Men series as in The Hunger Games.

-Dark Phoenix’s stated message — about how emotions make you strong and the dangers of repressing trauma — is totally at odds with Dark Phoenix’s actual content, in which Jean Grey spends most of the movie in fear of losing control of her powers, then getting angry, losing control, and accidentally hurting the people she loves.

-Do you remember in X-Men: Apocalypse when Jean Grey turned into a big fiery bird during the fight with Apocalypse? Because this movie does not.

-Do you remember in X-Men: Apocalypse when Quicksilver realized Magneto was his father and said they needed to talk about that? Because this movie does not.

Gallery — The Dumbest Sequel Subtitles Ever: