Long before the concept existed, the Duchess of Devonshire, Georgiana Spencer (Keira Knightley), was the original "It Girl." Like her direct ancestor Princess Diana, she was ravishing, glamorous and adored by an entire country. Determined to be a player in the wider affairs of the world, she proved that she could out-gamble, out-drink and outwit most of the aristocratic men who surrounded her. She helped usher in sweeping changes to England as a leader of the forward-thinking Whig Party. But even as her power and popularity grew, she was haunted by the fact that the only man in England she seemingly could not seduce was her very own husband, the Duke (Ralph Fiennes). And when she tried to find her own way to be true to her heart and loyal to her duty, the resulting controversies and convoluted liaisons would leave all of London talking.

"The Duchess" is the story of an extraordinary woman who rose to fame by staying true to her passions in a world of protocol, gossip and social rules – and paid the price.

Academy Award® nominee Knightley and Academy Award® winner Fiennes head an international cast that also includes Dominic Cooper ("The History Boys") as the abolitionist Charles Grey, the Duchess's favorite lover; Haley Atwell ("Cassandra's Dream") as the Duchess's alluring best friend and rival, Lady Elizabeth "Bess" Spencer; and Charlotte Rampling ("Swimming Pool") as the Duchess's mother, the Lady Spencer.

Rising UK director Saul Dibb ("Bullet Boy," "The Line of Beauty") brings to life a vibrantly lavish, yet rapidly changing England in the time of the Enlightenment, the French Revolution, and the madness of King George. The film is written by Dibb, Jeffrey Hatcher ("Casanova") and Anders Thomas Jensen ("After the Wedding") based on the award-winning biography Georgiana, Duchess of Devonshire by Amanda Foreman. The producers are Gabrielle Tana and Michael Kuhn. The executive producer is Carolyn Marks Blackwood.