The Duchess Trailer

Here comes another period piece for Keira Knightley. She stars in The Duchess, based on Amanda Foreman's best-selling novel, Georgiana, Duchess of Devonshire.

Keira Knightley plays the Duchess who is known for her extravagant political and personal life. She is trapped in an unhappy marriage with the Duke of Devonshire, played by Ralph Fiennes, and his live-in mistress.

She falls passionately in love with an ambitious young politician, played by Dominic Cooper, and the affair causes a bitter conflict with her husband and threatens to erupt into a scandal. The Duchess hits theaters on September 19th.