It's 1939 and the King of Navarre (ALESSANDRO NIVOLA) has returned from military maneuvers with an audacious plan for himself and his friends, Berowne (KENNETH BRANAGH), Longaville (MATTHEW LILLARD) and Dumaine (ADRIAN LESTER). The King wants them to devote themselves to a three year program of self-improvement that involves studying, fasting, little sleep and even less - in fact, no - romance.
As such, no women will be allowed in the court save for Holofernia (GERALDINE McEWAN), the King's principal tutor who, with the aid of Sir Nathaniel (RICHARD BRIERS), tries to improve the men's minds and spirits respectively. That plan runs into a serious complication, however, upon the arrival of the Princess of France (ALICIA SILVERSTONE) and her attendants, Rosaline (NATASCHA McELHONE), Maria (CARMEN EJOGO) and Katherine (EMILY MORTIMER).
Having heard of the King's decree, the Princess sends her assistant, Boyet (RICHARD CLIFFORD), to check on its validity, but the King and his friends are preoccupied with another development. A Spanish nobleman, Don Armado (TIMOTHY SPALL), has arrived in town and fallen for the voluptuous Jaquenetta (STEFANIA ROCCA) who was spotted with the court's vaudevillian clown, Costard (NATHAN LANE), thus defying the King's order.
Things become even more complicated when the four men and women finally meet and sparks immediately fly between the four potential couples. As the King and his men try to maintain their no-romance pledge, they must contend with incorrectly delivered love letters and other comic mishaps, the effort of trying to hide their feelings toward the women, and even the outbreak of WWII.