Bachelorette 

With her feature-film debut, playwright Leslye Headland makes a desperate attempt to squeeze a little more mileage from modern-day Hollywood’s most overused comic premise: Old friends get nuts and go through changes on the eve of a wedding.

And a little — just a little — mileage is what she gets. Bachelorette is basically Bridesmaids meets The Hangover with more coke. The old friends this time around are Regan (Kirsten Dunst), a bossy-pants queen bee; Gena (Lizzy Caplan), a gutter mouth; and Katie (Isla Fisher), an airheaded party girl.

The fourth member of the clique, Becky (Bridesmaids’ fabulous Rebel Wilson), may be the reason for the reunion, but she qualifies as a friend in, at best, a decidedly second-class sense. The other three women are affronted that she’s the first in the group to get married and refer to her as Pig Face behind her back, just as they did in high school.

The writer-director never does offer a plausible explanation regarding how or why the relationship among these mismatched women — three narcissists and a sweet, tubby nerd — would still exist more than a decade after graduation. Maybe that’s because Headland was preoccupied with her need to push the female raunch envelope, the only plausible reason for this movie to exist.

The problem is, she succeeds sporadically in the film’s first half and then caves to convention in the second. The opening scenes contain fleeting moments of wit and imagination. Regan’s attempt to milk her volunteer work with young cancer patients for praise at a lunch with Becky is edgy-ish. Flying to New York from LA, Gena strikes up a hilarious conversation with a male stranger on the politics of blow jobs. The evening before the wedding, the three decide to post a photo on Facebook of two of them fitting inside the bride’s dress. I’m not sure comedy history was made, but I chuckled here and there.

But then the dress gets damaged, and the balance of the picture is devoted to a night of zany escapades, as the trio chug and drug their way from one end of Manhattan to the other in search of someone to repair it. Fond memories of funnier films will likely be evoked as the ladies variously wind up in a strip club, require medical attention and behave badly on a bathroom sink.

I know what you’re thinking: no tiger? Evidently Headland’s saving it for the sequel. Good luck with that. However, her most unfortunate move in adapting her off-Broadway show for the commercial cinema was the decision to sell out totally in the final act. What’s the point of creating such defiantly unlikable characters if you’re just going to declaw them and give them hearts of gold before the closing credits roll? A better title might have been Girls Gone Mild.

Bachelorette, believe it or not, was conceived as part of a cycle of works based on the Seven Deadly Sins. This chapter was supposed to serve as a meditation on gluttony — though, unless my research is off, every one of the seven transgressions is committed by our bitchy BFFs. They may even have invented a couple of new ones.

My guess is that Headland’s freshman foray into moviemaking produced such uneven, ultimately forgettable results there won’t be six more films to line up for. She had something in that first act, but, from a Hollywood screenwriting point of view, what to do and where to go with it was a tricky proposition. She took the easy way out.

In the end, the moral of this story has more to do with a little cardinal sin called sloth.