“Masterminds”

Rated PG-13 (1:34)

**1/2

Opens today

There’s a certain subset of the population that may find Zach Galifianakis in a ridiculous hairdo the height of comedy. If you are in that segment, welcome, join us. You’ll find much merriment in the lightweight and very silly comedy “Masterminds,” which is astonishingly based on the true story of one of the largest cash robberies in the United States. Also, Galifianakis sports a variety of insane wigs and ’dos, from a long blond number to a kinky black perm to his own Prince Valiant bob, styled for the heavens.

“Masterminds” is a small, very strange film, and definitely doesn’t enter the upper echelons of director Jared Hess’ oeuvre, which includes wacky comedy classics “Napoleon Dynamite” and “Nacho Libre,” or even the best work of its stars. Nevertheless, the marriage of the insane 1997 true crime story and the murderer’s row of comic performers results in copious laughter.

Galifianakis plays aw-shucks naif David Ghantt, an employee of armored truck company Loomis Fargo, trapped in a loveless engagement with Jandice (an unblinking Kate McKinnon), and carrying a torch for his co-worker, sassy Kelly (Kristen Wiig). Kelly and her petty thief buddy Stephen (Owen Wilson) hatch a plan to rob the company vault, and ensnare lovelorn David into their plot as their inside man.

Despite a complete lack of skill or common sense, David pulls off the robbery, though soon he’s stranded on the lam in Mexico, while Stephen and his family are living high on the hog back in North Carolina, freely spending the millions David stole for them.

Hess’ approach is to give his comedic performers the time, space and permission to push the boundaries of their own bizarre tendencies. From Jack Black’s riffs in “Nacho Libre” to the deadpan ad libs of Jemaine Clement in “Don Verdean,” Hess creates spaces for comic weirdness to percolate, and it’s the perfect showcase for a comedian like Galifianakis, who can elicit belly laughs from a well-deployed glance or intonation from one of his very specifically rendered characters.

“Masterminds” offers plenty of opportunities for hilarious moments from the incredibly funny cast, which also includes two other “Saturday Night Live” performers, Leslie Jones and Jason Sudeikis. It’s a cast with which a filmmaker can just turn the cameras on and watch the madness unfold — whether it’s Wiig crooning a wordless love ballad into a walkie-talkie, an inspired take on an engagement photo shoot featuring David and Jandice, or simply Galifianakis on roller skates.

But there’s something about the slower, dry, Hessian tone working in concert with this high-octane heist story that doesn’t quite jibe. Perhaps it’s that this is the first film that Hess has directed that he hasn’t written (the script is by Chris Bowman, Hubbel Palmer and Emily Spivey), but it’s as if there are too many characters, too many plot twists, too many action-based, broad story moments, which ultimately curb the opportunities to really let these weirdos loose.

The film devolves into a schlocky ’90s unlikely-hero-saves-the-day routine, and fails to delve into deeper themes about crimes and punishment and passion. There’s also the unshakable feeling that, at times, the cast and filmmakers might be laughing at their small-town subjects rather than with them. Yet “Masterminds” still has its riotously funny moments, thanks to the fearless, uninhibited actors and a director who lets them play.