Grade: C

The best special effect in this adaptation of one of Marvel Comics’ second- or third-tier titles occurs at the very start, when Michael Douglas appears looking a good three decades—or more—younger than his seventy years. The sequence is astonishingly convincing, and puts the waxen version of the young Arnold Schwarzenegger that recently appeared in “Terminator Genisys” to shame.

None of the CGI that follows in Peyton Reed’s “Ant-Man,” about an incredibly shrinking superhero, is as good as this opening: the visuals are good enough, but slightly cheesy, as though the filmmakers were acknowledging that they’re not trying to raise the bar here. There are even moments—as in a shot of a hugely enlarged Thomas the Tank Engine, its eyes bobbing back and forth, toward the close—when they’re obviously winking at the absurdity of it all.

Nor does the movie fit comfortably into the hugeness of the rest of the cinematic Marvel universe. There’s a stray reference to the latest installment of “Avengers,” but the only one of that group’s members that appears—if you set aside the obligatory post-credits clip—is a second-tier one, the Hawk (Anthony Mackie). It’s obvious that “Ant-Man” is intended to serve, in more ways than one, as Disney-Marvel’s version of the shrimp little brother to the big guys. That’s fine in theory; the problem is that the movie’s almost self-deprecatory sense of tongue-in-cheek humility is matched by the fact that all the pleasures it affords are very small ones indeed. Some will argue, not without justification, that they’re as infinitesimal as its hero.

The essentially jocular nature of the enterprise was, of course, reflected from the start in the choice of Edgar Wright, whose bizarre take on things was reflected in his work with Simon Pegg and Nick Frost, to script and direct. He dropped out as director over “creative differences,” of course, and while he and Joe Cornish are still credited first as scripters, precisely how much of their work remains in thrown into question by the addition of Adam McKay (Will Ferrell’s collaborator) and Paul Rudd in that category. Rudd’s assumption of the title role also certifies the essentially genial nature of the enterprise: he’s basically a light comedian, after all, and brings that quality to the part of Scott Lang, the expert cat burglar and ex-con recruited by the original Ant-Man, Hank Pym (Douglas) to don his old suit and short-circuit the malevolent plans of Pym’s corporate successor Darren Cross (Corey Stoll) to weaponize the miniaturization technology in league with a villainous bureaucrat (Martin Donovan).

The mission involves lots of slapsticky training for Lang-Rudd, with plenty of comic pratfalls and bug-eyed reaction shots (pun definitely intended) as he learns to control the process of shifting size and is taught fighting techniques by Pym’s svelte, martial arts-trained daughter Hope (Evangeline Lilly), who’s also serving as her father’s mole in Cross’s company. Our miniature hero must also learn how to telepathically direct his army of helper ants—rendered in CGI with varying levels of persuasiveness—to do what they must to ensure his success in derailing Cross’s plans.

All of that is pretty standard-issue stuff straight off the Marvel “origins issue” assembly line. But “Ant=-Man” folds in a couple of other plot threads that are meant to add depth and humor but mostly weigh things down. One involves Lang’s domestic situation, with his ex-wife Maggie (Judy Greer, wasted) involved with cop Paxton (Bobby Cannavale, doing his smugly superior routine until he becomes a good guy at the end) keeping our hero, who’s way behind in his child support, from his doting, cute-as-a-button daughter Cassie (Abby Ryder Fortson). This business relies far too much on Fortson’s rather cloying lovability, and descends to the level of cheap child endangerment for suspense when she’s taken prisoner by Cross’s miniaturized alter-ego, the nefarious Yellowjacket, who uses her to lure Ant-Man into the inevitable final confrontation.

Then there’s the addition of three stooge-like buddies of Lang—motor-mouth Luis (Michael Pena), computer wizard Kurt (David Dastmalchian) and homeboy Dave (Tip “T.I.” Harris)—to the team assembled to break into the Cross Company and assist in Ant-Man’s sabotage of the shrinking process. These fellows are amusing in small doses—and one bit involving them, in which Pena’s recitation of events segues into flashbacks in which other characters are shown lip-synching to his words—is actually pretty clever, and dexterously pulled off. But like The Lone Gunmen in “The X-Files,” if too much running-time is expended on them, they can get tiresome; and they get lots of attention here.

More winning are Rudd, whose light touch constantly reminds us not to take the movie too seriously, and Douglas, whose grumpiness—once he gets to act his age after the opening bit—is mitigated by obvious concern for his daughter and continuing grief over the loss of his wife (her apparent demise explained late in the film). Lilly cuts a suitably elegant figure as Hope, and seems assured a prominent part in the presumed sequel signaled in the first of two closing-credits blurbs. On the technical side the picture is fine, even if the effects aren’t top-of-the-line; Russell Carpenter’s camerawork is spiffy, Shepherd Frankel’s production design more than adequate and the editing by Dan Lebental and Colby Parker Jr. trim. But Christophe Beck’s score is pretty generic.

There are points in “Ant-Man” where the scientific gobbledygook gets rather tedious, and others where explanation is tossed aside as too inconvenient to bother with. But that’s par for the course in these comic-book extravaganzas, and probably won’t seriously impede the picture from contributing, even if not at “Avengers” levels, to the financial juggernaut these superhero outings have come to represent for Marvel and now Disney. It seems a pity, though, that the screenplay didn’t have the guts to emulate the wonderfully ethereal close of its real progenitor, Jack Arnold’s “The Incredible Shrinking Man” (1957). It’s not that the opportunity is lacking: the sacrifice Lang makes at the close practically invites it.

But the filmmakers were probably right to reject the idea of leaving things in limbo if it ever came up. Audiences today seem unable to accept anything but a triumphantly happy ending, even if getting one means questions even the characters can’t answer, let alone the audience; and “Ant-Man” gives it to them while allowing plenty of options for the continuation of the story. In today’s market-controlled studio environment, that’s all that matters.