With Rachel Getting Married, young actress Anne Hathaway dirties and buries the prim-and-proper persona she’s created by starring in movies like The Princess Diaries and The Devil Wears Prada. Like Nicole Kidman’s character in last year’s Margot at the Wedding, Hathaway’s Kym is a force of nature whose neuroses wreak havoc on what is supposed to be a family celebration.

On leave from rehab, Kym returns home to attend her sister Rachel’s (Rosemarie DeWitt) wedding. There, she brags about her checkered past and turns on the emotional fireworks during the hectic wedding preparations. Early on, Kym reserves her biting one-liners for her sister’s maid of honor, Emma, but it is quickly revealed that her battles with Emma are just a warm-up for a more substantial showdown with her family.

One of the film’s most affecting scenes takes place during the wedding’s rehearsal dinner. There’s a crazy uncle wearing a red-and-white cowboy shirt with a comical speech. “We are gathered here to celebrate love pure and simple,” he says. “Rachel is pure. Sidney is simple.”

Needless to say, all of the toasts are about the soon-to-be-married couple until Kym’s speech. Kym boasts about making a knife out of her toothbrush in the hold and other transgressions before finally getting around to congratulating her sister. It’s obvious that she thrives on being the center of everyone’s attention.

While Kym clearly shouldn’t be the focal point of her sister’s wedding, Hathaway’s performance rightfully deserves to be the centerpiece of Rachel Getting Married. Hathaway is wholly believable as the skulking, chain-smoking Kym whether she’s having a sexual encounter in her family’s basement or finally revealing the dark truth behind her conflicted nature at a 12-step program. She imbues Kym with a perfect mix of bravado and vulnerability.

Most likely influenced by his recent forays into documentary (Jimmy Carter: Man From Plains, The Agronomist), director Jonathan Demme, best known for The Silence of the Lambs and Philadelphia, shot Rachel Getting Married with handheld cameras. It’s an effective strategy that allows the viewer to get up close to this dysfunctional family. At times, Rachel Getting Married plays like a Robert Altman film with different characters vying for the camera’s attention. Throughout, Demme coaxes superb performances from the cast– including Debra Winger as the siblings’ remarried mother who is clearly trying to disentangle herself from her messy family– that feel so natural it’s hard to believe they were scripted.

Demme’s one misstep is the wedding reception. Though Sidney (Tunde Adebimpe of the alt-rock band TV on the Radio) is a musician in the film, the reception comes on like a multicultural Lollapalooza with performances by English rock legend Robyn Hitchcock, reggae vocalist Sister Carol, a jazz band, a world music act and a DJ. It makes one wonder if Demme– who has made a handful of highly regarded films on rockers including Neil Young: Heart of Gold and the Talking Heads concert flick Stop Making Sense– has a compulsion to put musicians on film.

RACHEL GETTING MARRIED (3) Directed by Jonathan Demme. • Starring Anne Hathaway, Rosemarie DeWitt and Debra Winger. • R, 113 min. • At Osio Cinemas.