Bachelorette

At one point late in “Bachelorette,” Kirsten Dunst’s fiery yet weak-kneed creation inadvertently reveals an ugly old habit of hers to a near-total stranger. “I wanted to be beautiful,” she offers, by way of explanation.

Such a tender moment is rare in the boisterous and bobble-headed “Bachelorette,” a fizzy cocktail of women behaving very badly for no particular reason other than their constant need to feel validated. The film does not want to be beautiful, and it rarely is, nor does it ever find a manageable rhythm. But it is frequently entertaining, and wins laughs through sheer nerve.

The three protagonists, once inseparable in high school, now find themselves stumbling drunkenly into their approaching thirties: Dunst as the prickly, domineering, perfectly named Regan; Lizzy Caplan as the acerbic and monologue-prone Gena; and Isla Fisher, in a bust-accentuating strapless dress, as the frequently jazzed Katie.

Our trio is horrified to learn of their frenemy’s impending engagement, unable to stomach the insult that the least attractive of them (Rebel Wilson) would be the first to get married. Thus, the night before the wedding, they break out the cocaine and indulge in a few minutes of savage mockery, followed by several more hours of desperate, frantic attempts to undo the consequences of said mockery.

“Bachelorette” is directed by Leslye Headland, who also adapted the screenplay from her 2008 stage production [seen here at Studio Theatre] – a work originally presented as the “Gluttony” portion of a seven-play spin on Dante’s Seven Deadly Sins. Headland has expanded the action here so that what was once a naked outpouring of insecurities in a sparse hotel room is now a screwball expedition through Manhattan charted across One Long Night.

Few who wander into “Bachelorette” cold would be able to guess at its theatrical roots, for it bears every hallmark of a studio-meddled, marketer-approved Hollywood formula. The three leads boast plain, unchallenging story arcs, and find cures for their psychological ailments within the allotted 87 minutes. They ultimately pull off, in the improbable nick of time, a wedding ceremony that manages to be much more spotless than the preceding shenanigans should have allowed for. And they take part in a silly dance number at film’s close.

That said, there’s plenty to enjoy about “Bachelorette,” from the winning performances of the three leads (Fisher is a standout) to jokes about strippers and oral sex that are just the right shade of blue. And Headland squeezes in some striking, painful moments, as in Regan’s aforementioned self-purging.

These offset the film’s rougher patches, like a scene with a male stripper (Andrew Rannells of The Book Of Mormon fame) that lacks a comedic payoff, or the script’s heavy reliance on pop-culture to do the emotional heavy lifting.

Headland, who was indie film king Harvey Weinstein’s assistant for four years, is great at snappy dialogue (“No, I’m not doing anything,” Regan says over the phone mid-intercourse), but seems to have lost a touch of ambition. For the film debut of someone with a Dante-inspired seven-play cycle to her credit, isn’t it natural to expect something a bit… loftier than yet another goofy wedding comedy?

It was perhaps inevitable that “Bachelorette” would forever be wedded to the 2011 Kristen Wiig smash “Bridesmaids” in moviegoers’ minds, for richer or poorer. Both films concern themselves with women who lash out at their environments as a way to cope with growing fears of lifelong loneliness and dissatisfaction. It’s a rich and obvious concept for a female-driven comedy. Yet it appears more novel than it should, because Hollywood, unlike the theater, still has issues with assigning motives to female characters that don’t involve a male counterpart.

That impulse has not been entirely purged. All three leads in “Bachelorette” attain happiness at least partially with a man’s help. And in the case of the relationship between Gena and her ex-boyfriend (Adam Scott), who offers a rather lame justification for an unforgivable act he committed years before, this trope feels particularly strained.

But “Bachelorette” will not have to settle for merely bridesmaid’s status. The film earns its place for the way Headland gleefully rakes the hot coals of anger that bubble beneath the surface of such happy-seeming gal pals.

“Bachelorette” is now playing at AMC Georgetown, AMC Rio, AFI Silver Theatre and on VOD such as iTunes, Amazon, Comcast and DirecTV.