Perhaps you have a friend who's a little obsessive about weddings, perusing the Sunday social pages with unnatural interest, reading about other people's engagements and weddings as passionately as some folks follow their favorite sports teams. If you've never met a woman like this, you might not believe it's possible for a normal, intelligent woman to harbor such an obsession for the whole idea of weddings, but they do exist, and 27 Dresses delves into the world of one such fictional woman, Jane (Katherine Heigl), while also pulling of the rather neat trick of making the very attractive Heigl appear to be the less attractive, more serious older sister to sexy blond baby sister Tess (Malin Akerman, who previously was a bright spot on Lisa Kudrow's short-lived HBO series The Comeback).

We meet Jane as a child, at a relative's nuptials -- the beginning of her obsession with all-things-wedding -- when young Jane rescues a potential wedding dress disaster with the creative use of her sister's hair ribbon. When next we see her, Jane is all grown up and rushing back and forth between two weddings in one night, frantically changing clothes in a taxi as she charges back and forth across Manhattan in order to be there for both friends on their big days. And yes, it's a little unrealistic (have you ever tried to get by taxi from one part of Manhattan to another on a weekend night?), but it's also a pretty funny and well-edited scene that somehow manages to work. Jane, see, is obsessed with weddings. She's also the consummate older sibling who's spent her life taking too much responsibility for everyone except herself. She's the perfect older sister, the perfect friend, ever willing to do anything for everyone and never saying "no," which is partly why she's accumulated a collection of 27 hideously ugly bridesmaid dresses hogging a whole lot of closet space in her smallish NYC apartment (here you've got to suspend a little disbelief, because that closet -- not to mention the apartment would cost a whole lot more than she could afford as assistant to the boss)).

All is well (well, except for the noticeable absence of her own wedding to plan) in Jane's life, including the stability of her job as assistant to George (Edward Burns), her handsome, perfect boss with whom she happens to be secretly in love. George never notices Jane except as his ever-present, ever-reliable assistant, though (he's seemingly oblivious to Heigl's charm and beauty). And if this were a Nora Ephron film, we'd spend 90 minutes or so watching Jane save the day for her boss repeatedly until he miraculously realizes he's been in love with her all along, and wedding bells would ring, we'd collectively dab our eyes with a tissue, the end.

Thankfully, this story takes a bit of a different turn, introducing a couple of interesting twists into the mix, first in the form of Tess, who returns home from a modeling gig in Milan and catches George's eye at an office party when she shows up in a shimmery yellow sequined number that perfectly sets off her perfect tan, lovely blond hair, and sparkling blue eyes. Jane is seething with jealousy, but ever the good girl, restrains herself when George and Tess start dating and, ultimately, end up engaged -- and guess who Tess wants to be her maid of honor?

The other twist in the tale is Kevin (James Marsden, who I'm really starting to like after his turns in Enchanted and Hairspray), a cynical writer who hates weddings, even though his job is covering them in all their lace-and-frosting glory for the Style section of the New York Journal. Although Kevin loathes his job, he does it so well that women like Jane cut out and save his columns on couples' engagements to read over and over again his touching descriptions of happily-ever-afters. Jane catches Kevin's eye when she's at the wedding of the first friend in the big opening scene, when he sees her changing bridesmaid gowns in the cab and realizes what she's up to. They end up sharing a cab and a conversation that does not go well, when wedding-struck Jane realizes Kevin thinks weddings are lame (he neglects to confess that he writes about them for a living, and so she doesn't realize that he is the writer she obsesses over).

But Jane leaves her Filofax in the cab (kind of like the fairy tale glass slipper, only with wedding dates penciled in), and when Kevin sees how many weddings she's a bridesmaid for, he gets an idea for a cover story that could finally catapult him out of the hell of writing for the Commitments section for good. Trouble is (and of course you saw this coming, but it still works) he starts to kind of fall for Jane, and feel sorry for her plight as she is forced to plan her sister's wedding to the man she secretly loves.

All this makes for an interesting sort of tale that does a good job keeping the audience engaged (pun intended) from start to finish, and if the ending is kind of what you expected it would be, the ride was fun enough that you don't really begrudge the scribe and director too much for that, either. Mardsen and Heigl have a great chemistry, and the role of Jane really gives Heigl a chance to show off her comedic chops and prove that she's way more than just a pretty face. I like her playing playing the underdog to her ostensibly prettier younger sister, too. She just has a great, likable presence that simultaneously makes her attractive to men but not too threatening to women, which suits her well for rom-coms, and it works well in this film.

With Fox's decision to run 27 Dresses against Mad Money and Cloverfield this week instead of The Bucket List and Juno last week, it will be interesting to see how Heigl carries this film going up against the demographic-spanning appeal of the Mad Money cast.