‘Ant-Man’ smaller but still not fun size

If ever there was a sworn devotee — a chanting, face-painted worshipper — of the Big, it is Marvel.

So the prospect that Ant-Man, the miniscule Mighty Mouse of Marvel’s stable of powerhouses, might join the brawny big-screen ranks of the Hulk, Thor and the rest has long held some pleasing irony. But that enticement — Oh, if it was something different! — went out the helicarrier window when, just weeks before shooting was to commence, Edgar Wright, the British blender of genre and comedy who had worked on the project for eight years, departed over “creative differences” — a sacrifice, seemingly, to the Marvel colossus.

The precise source of the dispute is unknown, but it’s clear enough from the final product, pushed forward with the quick insertion of director Peyton Reed (“Bring it On,” “The Break-Up”) and a rewrite by Adam McKay and others, that “Ant-Man” became bedeviled with staying true to its more modest size and idiosyncratic nature, and with the larger, blander demands of being a Marvel movie complete with superhero cameos and (optimistic) sequel set-ups.

The result is a film not quite sure of itself, like it’s wearing clothes a size too big.

Paul Rudd plays Scott Lang, a politically motivated cat burglar being released after three years in San Quentin. He has an ethnically diverse group of petty criminal friends: Tip “T.I.” Harris, David Dastmalchian and Michael Pena, the only actor rightly convinced he’s in a comedy. Lang is trying to right himself for the sake of his young daughter, Cassie (Abby Ryder Forston), and for paying child support to his ex-wife (Judy Greer, an actress too good to be twice relegated to the domestic sidelines in this summer’s blockbusters).

But spryness (an essential quality for any movie about an insect superhero) or any much purpose, at all, is missing from these scenes. The movie is too controlled for Rudd’s goofball charm — best on display when simply standing in front of a mirror (“Wanderlust”) or animated about music (“I Love You, Man”) — to break free.

Through some strained plot mechanics, Lang is recruited by the original Ant-Man, the scientist Hank Pym (Michael Douglas), to succeed him in the suit. Along with his daughter (a bob-sporting Evangeline Lilly), he’s conspiring to prevent a former apprentice (Corey Stoll) from unlocking the atomic secrets that led to Ant-Man in the first place: the ability to shrink down to bug-size, yet maintain strength. Somewhere in Wonderland, Alice is tapping her foot.

With the press of a button, he can toggle between big and small, and appear all but invisible when tiny. The perspective change allows for some unlikely superhero foes, like a bathtub drain. During training, while Lang tries to perfect his communication with other underground ants, he sometimes pops out of the ground like a sprouted cabbage.

With a screenplay credited to Wright, Joe Cornish, McKay and Rudd, “Ant-Man” unfolds in pleasingly human-sized fashion. It’s a heist movie. Not one city is leveled; it’s like Marvel has gone on a diet.

But it’s only in the climactic scenes where the movie unlocks the antic potential of its shape-shifting. Rather than taking place above the skyline of a metropolis, the big action scenes are set inside a briefcase and in Cassie’s bedroom. Such moments, sprinkled throughout, are like glimpses of a better “Ant-Man” that might have existed.

Change, we are told, is afoot in the Marvel Cinematic Universe. “Ant-Man” is the final movie in the studio’s “Phase Two,” with promises of bigger, intergalactic battles looming in “Phase Three.” But as a parent might say, it’s just a phase.

Because you have to squint pretty hard to spot the differences from Marvel movie to Marvel movie. If “Ant-Man” proves anything, it’s that any diversion in this universe is likely to get stomped underfoot.