At the Battle of Lewes, Henry III and his brother-in-law Simon de Montfort, fight for the mastery of England. Henry claims he has a divine right to rule; de Montfort and his Barons deny that a King may govern beyond the law. After the King's defeat, his son, the captive Lord Edward, plots with his Marcher Lords, while Simon finds that old loyalties to the Crown die hard. Before he is defeated at Evesham, de Montfort takes the startling step of summoning to Parliament, for the first time in history, representatives of the common people of England.