It is a truth universally acknowledged that an 18th-century beauty must be in need of a rich, neglectful husband, a smoldering lover and a fabulous wardrobe.

These verities, which have sold countless Harlequin Historicals, form the foundation of "The Duchess," a polished dramatic fable about Georgiana, the Duchess of Devonshire. Glamorous, populist, a media darling beloved by her subjects, unhappy in love, she was Princess Di 200 years before the fact.

We meet Georgiana (Keira Knightley) as a coltish teenager, organizing foot races among her many young suitors for the amusement of her friends. She's more than fond of her favorite, handsome young Charles Grey (Dominic Cooper, "Mamma Mia!").

Still, she is enough a creature of tradition to be thrilled when her mother, Lady Spencer (Charlotte Rampling), brokers her to William Cavendish (Ralph Fiennes), Fifth Duke of Devonshire and one of England's wealthiest landowners. Devonshire needs a male heir and, as Lady Spencer assures the Duke, women in her bloodline have never failed to produce. He offers a thin lemon slice of a smile in reply and we sense that this will not be one of history's grand passions.

Georgiana's romantic disillusionment arrives swiftly. The Duke is not an evil man, just chilly. He has mistresses to attend to his desires and his wife to bear him children, and any frivolity about love is outside his emotional boundaries.

He has less interest in his young wife than in his hunting hounds. It's one of the grace notes of the script co-written by Minneapolis dramatist Jeffrey Hatcher ("Casanova," "Stage Beauty") that our hearts go out to Georgiana, yet we can sympathize with the Duke. He's an honorable man and supporter of progressive Tory policies extending greater freedom to the masses. He loves mankind; it's people he can't abide. He watches others with a detached, godlike gaze. When he tires of a formal dinner, he simply stands up and walks off without a word. Who hasn't wanted to do that?

The life of position and privilege that his bride imagined is in fact a breathtakingly beautiful prison of icy palaces and hedge mazes. This is a world where every emotion is beneath the surface, constrained behind extravagant costumes, wigs and makeup. Georgiana makes the best of her gilded cage, cultivating friendships with the wittiest politicians, playwrights and partygoers in London. Lady Bess Foster (Hayley Atwell), an older, attractive divorcée and her new best friend, catches the Duke's eye, and Charles Grey, now a rising force in Tory politics, becomes a regular visitor to Georgiana's elegant circle. All the pieces are in place for confrontations, betrayal and heartbreak as the Duchess must choose between position, family and rash, socially inappropriate love.

"The Duchess" gives us a gorgeous world, a detailed picture of a time and place that could have been painted by Constable, Gainsborough or Watteau. But you wouldn't want to live there.

Colin Covert • 612-673-7186