Simon Kinberg takes a second crack at the so-called Dark Phoenix Saga that Chris Claremont and John Byrne created for the X-Men comics in the late seventies and early eighties, this time serving as director as well as writer and producer. Unfortunately, “Dark Phoenix” proves little more successful than the first time around, Brett Ratner’s “The Last Stand,” was back in 2006, though fans might applaud the fact that it’s marginally more faithful to its source than the earlier version, which just folded Jean Grey’s story tangentially into a larger one.

In Kinberg’s slimmed-down account, telepathic Jean (Sophie Turner) is part of the celebrated X-Men team that operates under the command of paralyzed Professor Charles Xavier (James McAvoy), having come somewhat to terms with her guilt over feeling responsible for the deaths of her parents (Scott Shepherd and Hannah Anderson) in a car crash when she was eight (played as a girl in the flashbacks by Sommer Fontana). She’s been raised by Xavier since then.

Now she serves as part of the mission sent to rescue the crew of the Space Shuttle, which has suffered some sort of accident and is whirling helplessly above the earth’s atmosphere. The endeavor, headed by wonky Hank McCoy/ Beast (Nicholas Hoult), also includes Raven Darkhölme/Mystique (Jennifer Lawrence), Scott Summers/Cyclops (Tye Sheridan), Ororo Munroe/Storm (Alexandra Shipp), Kurt Wagner/Nightcrawler (Kodi Smit-McPhee) and Peter Maximoff/Quicksilver (Evan Peters). Using their special abilities, they save the crew, but in the process Jean becomes infused with the power of the mysterious cloud that disabled the Shuttle, endowing her with strength so great that even Hank cannot measure it.

To complicate matters further, Jean becomes aware that Charles has misled her about the crash that killed her parents. She goes off in search of the truth, and when her comrades follow to bring her back, she unleashes her new abilities against them, with tragic results. A visit to the idyllic camp that Erik Lehnsherr/Magneto (Michael Fassbender) has set up for his mutant followers has an equally disastrous outcome The upshot is that all the X-men are soon in pursuit of Jean, some hoping to save her and others to destroy her.

But she’s being sought by someone else as well—an alien called Vuk (Jessica Chastain), the leader of a group of space refugees whose empire was wiped out by that mysterious cloud and, having taken on human bodies, are now intent about extracting its power from Jean for their own purposes.

Much fighting—among the X-Men themselves, between them and Jean, with the army, and against the aliens—ensues, featuring many special effects of unexceptional quality. The big finale occurs aboard a train where the captive X-Men must face off against Vuk’s forces and Jean makes a final decision about her fate.

What’s most surprising about “Dark Phoenix,” given its place as the purported final installment of a lengthy series that goes back to Bryan Singer’s 2000 original and has witnessed numerous spin-offs and a good deal of chronological tweaking (another spin-off, “The New Mutants,” will be released next year), is how purely functional it seems. There’s little imagination or inventiveness to either the story or the telling of it; the result is a curiously pallid send-off for the characters. The previous installment, “Apocalypse,” was silly, stentorian and bombastic, to be sure, but at least it aimed for a degree of grandeur. Kinberg doesn’t even try; he’s content with a narrative, and execution, that feel utterly ordinary and generic.

The cast don’t give their best either. The regulars go through their paces as if they were doing chores (Lawrence has very little to do, and Peters’ Quicksilver seems simply to disappear abruptly midway through); the sleepy Turner, who takes center stage here, is especially soporific. The most embarrassing performance, however, comes from Chastain. True, Vuk is meant to be an emotionless sort of being, but the actress takes her to the point of absolute blandness. That makes for a picture in which neither the accidental anti-heroine nor the accidental villain is up to snuff.

The technical contributions are pretty flat as well, from Claude Pare’s production design and Mauro Fiore’s cinematography to Hans Zimmer’s score. And as mentioned, the effects are at best middle-grade; unlike “Apocalypse,” this hardly looks like a $200 million production.

Fans who have stuck with the X-Men franchise for nearly two decades might have hoped that their story would end with a bang, but “Dark Phoenix” is more of a cinematic whimper. It’s not as bad as John Trank’s “Fantastic Four” debacle, but it certainly doesn’t bode well for any future directorial aspirations Kinberg might harbor.