The cinched corsets, the mountains of upswept hair, the richly textured, intricately detailed costumes. Sure, "The Duchess" is a lavish exercise in style over substance, but it's a well-crafted, superbly acted one.

Keira Knightley brings her usual bright energy and sly charm to the role of Georgiana Spencer, the Duchess of Devonshire, and she manages to finds the subversive humour within the unassuming, artistically solid direction from Saul Dibb. Unsurprisingly, the star of "Pride & Prejudice" and "Atonement" seems perfectly comfortable in yet another period piece; this one begins in 1774 England, when Georgiana was a 17-year-old bride.

But the filmmakers -- and the movie's marketing machine -- are obviously trying hard to make the picture seem contemporary by pushing the idea that Georgiana was the first "It Girl," with her elaborate parties and influential fashion sense. It also doesn't hurt their argument that she was an ancestor of Princess Diana, who similarly was trapped in a loveless royal marriage and found herself the topic of endless gossip. It's a smart tactic. Considering our all-consuming obsession with celebrity, such a connection unfortunately doesn't seem too tenuous.

Working from the 1998 biography "Georgiana, Duchess of Devonshire" by Amanda Foreman, Dibb and fellow screenwriters Jeffrey Hatcher and Anders Thomas Jensen play up Georgiana's glamour and the tragically soapy elements of her life, all of which makes for compelling viewing.

But they don't delve deeply enough into the darker parts of her personality, such as her proclivities for drinking and gambling. You're sometimes left wondering what truly drives her, beyond a sense of propriety and a love for her children -- all girls, for a while, to the dismay of her distant husband, who yearns for a male heir.

Georgiana displayed an inquisitiveness and, with the Whig Party, a political activism that was unheard of among women at the time. (In using her popularity to campaign for Charles Grey, who would go onto become her lover as well as prime minister, she calls to mind Oprah Winfrey's high-profile support of Barack Obama.) A bit of enlightenment as to what inspired this true maverick might have been helpful.

Whatever she's doing, though, she's impossible to stop watching, both by her subjects as well as the audience. Part of the fascination comes from trying to figure out just how this stick figure of a star can possibly stand upright beneath the towering wigs and layers of clothes. Mainly, though, Knightley makes you feel Georgiana's initial giddiness as well as her eventual pain.

Early on, she's thrilled to have been chosen to marry the much-older Duke of Devonshire (Ralph Fiennes). As she gushes to her mother, Lady Spencer (Charlotte Rampling, who is withering in just a few scenes). "He loves me? I've only met him twice!" It doesn't take long for G, as she's known, to figure out that he loves his hunting dogs more. Fiennes is chilling as the exceedingly pragmatic duke, but he's also nuanced enough as an actor to convey some much-needed glimmers of humanity within this seemingly bloodless figure.

And so G seeks out her own happiness in various forms, all of which are taken from her in time. She invites her best friend, Lady Elizabeth Foster (Hayley Atwell), into their home, only to see her become the duke's lover. Her dreams of a life with her secret love, Charles (Dominic Cooper of "The History Boys"), are societally impossible.

What would Paris Hilton do? Whatever she wanted, of course. "The Duchess" harkens vividly to a time when women didn't have that luxury.

Three stars out of four.