The play spans only the last two years of Richard's life, from 1398 to 1400. The first Act begins with King Richard sitting majestically on his throne in full state. We learn that Henry Bolingbroke, Richard's cousin, is having a dispute with Thomas Mowbray, and they both want the king to act as judge. The subject of the quarrel is Bolingbroke's accusation that Mowbray had squandered money given to him by Richard for the King's soldiers. Bolingbroke also accuses Mowbray of the recent murder of the Duke of Gloucester, although John of Gaunt—Gloucester's brother and Bolingbroke's father—believes that Richard himself was responsible for the murder. After several attempts to calm both men, Richard acquiesces and Bolingbroke and Mowbray challenge each other to a duel, over the objections of both Richard and Gaunt.
The tournament scene is very formal with a long, ceremonial introduction. But Richard interrupts the duel at the very beginning and sentences both men to banishment from England. Bolingbroke is originally sentenced to leave for ten years, but Richard changes this to six years, whereas Mowbray is banished forever. The king's decision can be seen as the first mistake in a series that will lead eventually to his overthrow and death. Indeed, Mowbray predicts that the king will fall sooner or later at the hands of Bolingbroke.
John of Gaunt dies and Richard II seizes all of his land and money. This angers the nobility, who accuse Richard of wasting England's money, of taking Gaunt's money (which rightfully belongs to Bolingbroke) to fund a war in Ireland, of taxing the commoners, and of fining the nobles for crimes their ancestors committed. Next, they help Bolingbroke secretly return to England and plan to overthrow Richard II. However, there remain some subjects faithful to Richard, among them Bushy, Bagot, Green and the Duke of Aumerle (son of the Duke of York), cousin of both Richard and Bolingbroke. King Richard leaves England to administer the war in Ireland, and Bolingbroke takes the opportunity to assemble an army and invade the north coast of England. He executes Bushy and Green, and wins over the Duke of York, whom Richard has left in charge of his government during his absence.
When Richard returns, Bolingbroke first claims his land back but then additionally claims the throne. He crowns himself King Henry IV and Richard is taken into prison to the castle of Pomfret. Aumerle and others plan a rebellion against the new king, but York discovers his son's treachery and reveals it to Henry, who spares Aumerle as a result of the intercession of the Duchess of York but executes the other conspirators. After interpreting King Henry's "living fear" as a reference to the still-living Richard, an ambitious nobleman (Exton) goes to the prison and murders the former king. King Henry repudiates the murderer and vows to journey to Jerusalem to cleanse himself of his part in Richard's death.