PHOTO © MARVEL

What do you do with a Marvel movie that’s just sort of average?

Such is the dilemma of “Ant-Man and the Wasp: Quantumania,” the third solo outing for the titular insectoids — and the 31st proper film in the gargantuan Marvel Cinematic Universe. Parts are entertaining; others are not. Some aspects of the film’s design and production are dazzling; others are uninteresting. Some performers find ways to shine; others seem overwhelmed by all those green screens, wandering through a movie they know will be constructed around them at a later date.

In short: It’s average.

It’s a bit of a side quest, as the title heroes (Paul Rudd and Evangeline Lilly) find themselves unexpectedly sucked into the Quantum Realm, a universe that exists at a subatomic level outside of conventional space and time. They’re dragged to the tiny locale — along with the extended family, played by Michelle Pfieffer, Michael Douglas and Kathryn Newton — to discover a society full of Lilliputian weirdos living in fear and turmoil.

How, or why, there’s a rogue’s gallery of species and creatures in the Quantum Realm is not explained. We’re too busy turning our attention to the bad guy: Kang the Conqueror (Jonathan Majors), a universe-hopping tyrant in exile. The superhero family can help Kang with the science and/or magic whatsits he needs to escape, so he’ll harass, blackmail and torture them to gain their assistance.

It’s at once a self-contained story and a stepping stone; Kang, or a version of him (stick around through the credits, because the timeline is getting soupy), is set up to be the next great Avengers foe. While this particular encounter does have a beginning, middle and end — of sorts — we’re clearly here to introduce the villain to a wider audience. (A different Kang showed up in the Disney Plus series “Loki,” because there’s always more to the story with this much content being churned out.)

The good news is that Majors dominates the screen, proving not only why he should be a major player in the franchise but also promising years worth of nail-biting confrontations. The bad news is that most everyone who’s been around for a while looks tired; Rudd charms, as he always does, but Lilly, Pfeiffer and Douglas seem to be yearning for their trailers.

There are times when “Quantumania” is a thrilling, “Star Wars”-esque adventure with the heroes on hostile and unfamiliar turf, surrounded by weird creatures and constant danger. After a while, though, the admittedly imaginative vistas and new baddies all start to run together into a PlayStation-esque sorbet of color and action.

It’s not bad; with endless resources, a seasoned storytelling conglomerate and a stacked cast, it can’t be. I’d even call it good enough. But it’s just sort of average — which, for Marvel, is decidedly below average.

My Rating: 6/10

“Ant-Man and the Wasp: Quantumania” is now playing in theaters.