Though most Marvel superhero movies deal with threats to the whole planet, if not the entire universe, they’re all really about nothing more than providing juvenile thrills on a bloated scale. The initial Ant-Man movie, by contrast, didn’t claim to be concerned with anything but a fairly small crisis, befitting the petite size of the costumed protagonist, and while it didn’t eschew excitement, it was more about laughs.

The follow-up, which adds a superheroine to the mix, remains largely localized and comic as well. But being a sequel, it’s also bigger, with more extended action sequences and elaborate special effects. That’s not necessarily a good thing; in this case, however, it’s not fatal: “Ant-Man and the Wasp” is amusing enough to squeak by, though it’s overly busy and frantic, and the occasional attempts to fold it into the larger Marvel Universe (as in one of the end credit inserts) weigh it down.

As the movie opens, Scott Lang (Paul Rudd), the ex-thief recruited to be the new Ant-Man by the old one, genius inventor Hank Pym (Michael Douglas), is finishing up his house arrest for his role as part of the Captain America faction of the “Civil War” fracas; he’s trying to keep up a close relationship with his darling daughter Cassie (Abby Ryder Forstan), who’s living with his supportive ex-wife Maggie (Judy Greer, wasted) and her new husband Paxton (Bobby Cannavale, ditto). Meanwhile goofy FBI agent Jimmy Woo (Randall Park, pressing his dopey shtick too far) tries to catch Scott in any infraction that could extend the sentence.

But Lang is drawn into helping Pym, still angry with him for misusing the Ant-Man suit, and his daughter Hope van Dyne (Evangeline Lilly), now outfitted as The Wasp, in their effort to extract Hank’s ex-wife Janet (Michelle Pfeiffer), the original Wasp, from the Quantum Realm, the miniscule nano-world where she was trapped thirty years earlier, having shrunk to infinitesimal size to stop a runaway nuclear missile. Much of the humor lies in Scott’s having to get back home, where a giant ant has been assigned to wear his ankle bracket, in time to foil the FBI’s repeated attempts to catch him violating the terms of his sentence while helping Hank and Hope.

The frenzied action that follows juxtaposes the trio’s effort to rescue Janet with plot threads involving other characters. One focuses on Scott’s goofy partners in a would-be security agency—Luis (Michael Peña), Dave (Tip “T.I.” Harris), and Kurt (David Dastmalchian). In another, Ava, aka The Ghost (Hannah John-Kamen), a desperate young woman whom an accident conducted by her father, a former colleague of Pym, doomed to a precarious existence of phasing in and out of physical space, is determined to access Pym’s lab in order to cure herself; that strand also implicates another old colleague of Pym, an academic named Bill Foster (Laurence Fishburne). Then there’s nasty Sonny Burch (Walton Goggins), a trafficker in high-tech equipment, who also wants to get his hands on Pym’s lab.

That lab provides one of the movie’s cutest effects: not the interior, which is pretty generic despite a long tube that will lead to the Quantum Realm, but the exterior—the whole building can be miniaturized and carried off like a boxy suitcase. (The gag is overused, being applied also to cars and vans, but it’s still a good one.)

Other genuinely funny bits also involve transformations of a sort. In one case, Pfeiffer’s character takes over Rudd’s body from the quantum world to correct a mathematical formula, and Rudd’s impersonation of her clipped delivery is a gem. Then there’s the episode in which Luis, under the influence of a “truth serum” (itself the subject of some funny dialogue), recites a long account of past events, accompanied by a montage of flashbacks in which the people he’s talking about lip-synch to his voice. Peña’s rapid-fire delivery sells the bit, even though it’s a repeat of one from the first movie.

Much of the humor in “Ant-Man and the Wasp,” though, is pretty juvenile, with the FBI stuff particularly flat, though most of the material with Goggins, doing his usual sleazy routine, is also awfully thin. Rudd gets off a few good quips, like one in which he ridicules the scientific mumbo-jumbo by asking whether they’re just putting “quantum” in front of everything (perhaps he wrote the line himself), but a lot of the dialogue is no great shakes.

The effects are similarly hit-and-miss. The best one in the first movie was making Michael Douglas look young in the flashbacks. That’s still the case here, and it’s applied briefly to Pfeiffer as well (the younger Fishburne, on the other hand, is played by his son Langston). By contrast the rest of the VFX is solid enough (the exception being when Ant-Man switches to giant mode near the close), but—apart from the in-and-out-of-phasing of Ghost, whom Kamen plays with a degree of intensity that seems suited to a different, more serious movie—unremarkable. Still, the relative cheesiness feels of a piece with the whole movie, which lacks the titanic grandiosity and self-important tone of most Marvel product.

Otherwise the technical aspects of the movie are fine, with Dante Spinotti’s cinematography and the editing by Dan Liebental and Craig Wood doing a reasonably good job of coping with the jumpy narrative and splashy effects.

Though in every respect a lightweight addition to the Marvel canon, the innocuous “Ant-Man and the Wasp” is mildly enjoyable. By the way, if it’s Ant-Man, shouldn’t it be Wasp-Woman? Just asking.