The “Men in Black” franchise has been dormant for seven years, and in bringing it back screenwriters Art Marcum and Matt Holloway appear to have had the interesting idea to meld the high-concept formula of the first three movies with that of a Hollywood screwball comedy of the forties and fifties. A pity they, director F. Gary Gray and the special-effects team have proven so maladroit in fleshing out the notion. “Men in Black: International” turns out to be just another frenzied, overblown action comedy that curdles whatever nostalgia-based affection one might have harbored for the original movies. Part sequel and part reboot, it’s more “Wild Wild West” than the first “MIB.”

The sparkplug of the story, in tune with the contemporary rush to get rid of male dominance in the action-superhero world, is Molly (Tessa Thompson), who as a little girl (Mandelya Flory) helped a cute little Gremlins-like alien escape capture while her parents were zapped with a neuralyzer to forget its invasion of their home. Ever since that experience, she has been determined to become a member of the the MIB force, and through pluck and smarts she eventually finds her way into the agency’s American headquarters. (Precisely how she does so is mired in incomprehensible terms, but that becomes part of the script’s pattern.) Their head honcho Agent O (Emma Thompson) is so impressed that she takes her on as a probational hire, Agent M, and sends her off to the London office, where she’s welcomed effusively by High T (Liam Neeson), the department head there.

M quickly worms her way into the position of assistant to the office’s bad-boy superstar Agent H (Chris Hemsworth), who had partnered with T some time before (how much is never made clear: references to the event in the picture range from a couple of months to several years) in defeating the alien force called The Hive atop the Eiffel Tower. H has become reckless and boozy in the meantime, but T has a soft spot for him, and assigns him to protect Vungus the Ugly (Kayvan Novak), an important visiting alien who has a vital secret to disclose.

Of course H and M bungle the job as the result of the intervention of powerful twins (Laurent and Larry Bourgeois) presumed to be in league with The Hive, though in the process she pockets a little star-shaped device that proves the Key to Everything, the equivalent of the eternity stones Thanos fought the Avengers for, but all in one package.

To uncover the secret of the device they travel to Marrakesh, where they pick up as a sidekick a plucky CGI creation called Pawny (voiced by Kumail Nanjiani), the last surviving piece of a living alien chess set, and then must retrieve the dingus from the clutches of Riza (Rebecca Ferguson), an estranged old flame of Agent H and extraterrestrial weapons merchant, at her island fortress in the bay of Naples.

By this time, however, our heroes have come to suspect that there is skullduggery within the MIB itself—could smarmy Agent C (Rafe Spall) be the culprit conspiring with The Hive? The answer comes in another confrontation in Paris, where Agents H and M must work together to save the earth—and other planets—again. By then, of course, their adventures have engendered a romantic spark between them.

On the one hand “MIB: International” is a fairly typical example of the Hollywood action comedy of today, an episodic adventure that careens from one big set-piece to another to create a cinematic amusement-park ride. But it’s a poorly-constructed example of the type—the first half-hour is so sloppy that it feels like two or three separate movies carelessly tossed together, the links between them explained only later, and the following ninety minutes aren’t much better. The final confrontation, moreover, is an overlong dud.

It certainly doesn’t help that the special effects are chintzy. That might be deliberate, a sort of send-up of the genre, but it’s still hard not to be distracted by the decidedly imperfect green-screen work and creature effects that range from cheesy rubber masks to sloppy CGI. The exception is Pawny, who’s enjoyably voiced by Nanjiani and given the vast majority of the script’s amusing lines. He should be a hit with the kids, and will probably earn a place as a popular plastic toy.

Only slightly more successful is the screwball comedy between M and H—based, of course, on the clash of his raffish bravado and her ebullient naïveté. The problem here is that while Thompson is engaging enough, Hemsworth is way over-the-top; he has the stuff for comedy, as his Thor has shown (indeed, in his last stint as the Asgardian he and Thompson showed real chemistry), but in this case Gray has encouraged him to mug and preen so much that what begins as charm soon turns to irritating bluster. As for the others, Neeson is a bit of a pompous bore, the older Thompson spits out her lines efficiently, and Spall is oily enough to earn everyone’s dislike. Ferguson has fun camping it up, but the big fight scene in her fortress is not well staged.

There may be those who still have a soft spot for the “Men in Black” franchise, despite the mediocrity of the second and third installments. But nostalgia has its limits, and it’s doubtful it will carry this busy but blundering fourth episode to a point that would justify a fifth.