Against the backdrop of the savage Catholic/Protestant wars, Marie de Mézières, a beautiful young aristocrat, finds herself married to a young prince she does not love, haunted by a rakish suitor Gaspard Ulliel from her childhood, and advised by an aging nobleman Lambert Wilson, harboring his own forbidden desire for her. The Princess of Montpensier must struggle passionately to stay alive in the intrigue of this corrupt political and romantic web of duty, passion, religion and war.