She seems fine, but her powers -- that include telekinesis -- are now off the charts, worrying Hank McCoy (NICHOLAS HOULT), a.k.a. the Beast, who's run her medicals, as well as her boyfriend, Scott Summers (TYE SHERIDAN), a.k.a. Cyclops. And Charles' need for X-Men heroics has grown quite worrisome to Shape-shifter Raven (JENNIFER LAWRENCE). All of that comes to a head when Jean's powers continue strengthening, coupled with her discovery that Charles previously built mental walls in her head to protect her from a traumatic past.

Things get worse when a number of extraterrestrials --who've taken human form and are led by Smith (JESSICA CHASTAIN) -- arrive and want Jean's powers. And they're not the only ones looking for her. Due to those powers resulting in the accidental death of one of the X-Men, Hank seeks out Magneto, a.k.a. Erik Lehnsherr (MICHAEL FASSBENDER), to help him find and kill Jean before she does more damage. In response to that, teleporter Kurt Wagner (KODI SMIT-McPHEE), a.k.a. Nightcrawler, weather master Ororo Munroe (ALEXANDRA SHIPP), a.k.a. Storm, and Peter Maximoff (EVAN PETERS), a.k.a. Quicksilver, join Charles and Scott in trying to stop them as well as the aliens.

Despite nothing about any of that being good in real life, such behavioral changes, the reactions to them and the related thematic elements have been fodder for movie storylines over the decades and the latest, albeit somewhat unlikely, one to tackle that is "Dark Phoenix."

It's the latest and supposedly last installment -- at least of this most recent iteration -- of the X-Men series that's had its ups and downs in terms of quality since kicking off with 2000's "X-Men" and running through 2016's "X-Men: Apocalypse," with some spin-off ("Deadpool") and single character pics ("The Wolverine" and "Logan") along the way.

In my review of "Apocalypse" I noted that those behind the series should have followed the old sage advice of Kenny Rogers and known when to fold 'em and walk away, especially after the superlative "X-Men: Days of Future Past" (as well as "Logan" which should have received more Academy Award nominations than it did).

Alas, this new film will have many a critic and regular moviegoer hearing, once again, Kenny singing that song as you always want to end a film series on a high note (such as "Avengers: Endgame") rather than one that pretty much limps to its conclusion. That's not to say this offering from writer/director Simon Kinberg isn't without its share of action, as it has some decent sequences of that.

It's just that the rest of the script is lackluster, the villain and her goal are not particularly noteworthy, and the aforementioned thematic element storyline of dealing with a family member/friend turning bad isn't explored in a convincing or emotionally engaging enough way for us to care.

That character is Jean Grey (Sophie Turner) who, during a space shuttle rescue sequence, ends up exposed to some sort of alien energy force high above Earth. Already known for having problems dealing with her telepathic and telekinetic abilities, this development only exacerbates that issue and results in different reactions from those who know her.

Raven (Jennifer Lawrence, having the appearance and demeanor of someone contractually obligated to show up in yet another of these films) is worried, especially since she believes that their leader, Charles (James McAvoy), is putting the team at risk in relation to seeking further fame and adulation (in some verbal exchanges that feel clunky and violate the old "show, don't tell" rules of screenwriting).

After something bad happens as related to Jean being unable to control her anger and growing powers, Charles still wants to help her, as does her boyfriend, the ocular laser shooting Scott (Tye Sheridan). But Hank/Beast (Nicholas Hoult) is so mad that he tracks down Erik/Magneto (Michael Fassbender, still bringing class to the role and the film series in general) and they set out on a killing mission, thus putting them at odds with the others including Storm (Alexandra Shipp), Quicksilver (Evan Peters) and Kurt/Nightcrawler (Kodi Smit-McPhee). (On a side note, the latter still gets the best moments in the various action scenes, zipping here and there via instant teleportation).

During all of that, Jessica Chastain (seemingly channeling otherworldly Tilda Swinton at times) shows up as an extraterrestrial in human form who wants to get her hands on the energy that Jean now possesses in order to repopulate her kind on Earth, current inhabitants be damned. Alas, none of that's interesting or engaging in the slightest, while the fallen character storyline -- while driving the plot -- isn't explored satisfactorily or with enough depth as needed.

The result is an offering that occasionally features some exciting moments here and there, but otherwise feels dull and only points out how some of the past entries in the series were so much better. It's a good thing this is the last installment of this version of this series because, just like people have to do with those close to them who can't be saved, it was otherwise time to cut these mutant folks loose. Unlike the Avengers who went out with a bang, the X-Men go out with a whimper in "Dark Phoenix" that rates as a 4.5 out of 10.