The Duke of Gloucester, the King's uncle and arch-enemy, has been murdered. Most people suspect Thomas Mowbray did it at the King's command. Henry Bolingbroke, the King's cousin, has accused Mowbray to his face. Together they are summoned before Richard II.

The Percy family, Henry Bolingbroke's chief allies in deposing and murdering Richard II, have been cheated of their just rewards and now plot to overthrow the King. Worcester, the architect of their rebellion, arranges a meeting in Wales to decide how Great Britain will be divided among them. The King's army, part of it commanded by Prince Hal, marches westward to encounter the rebels. Even Sir John Falstaff receives a commission and marches off to join the battle at Shrewsbury.