At his palace in London, Henry sits in court with his various lords. Suffolk has returned from France with Margaret, whom he presents to the king as his new wife. He also brings a peace treaty from France. Gloucester reads the treaty, but he falters when he comes to a passage about the French keeping the territories of Anjou and Maine in return for Margaret. Gloucester is upset at this loss of land recently won by Henry V and defended in the recent French wars. He prophesies the imminent loss of France and leaves.

With Gloucester gone, Cardinal Winchester suggests to Buckingham and Somerset that they plot to oust him. Once they leave, Salisbury and Warwick then talk with York about trying to suppress the influence of Suffolk and Winchester. York is then left alone, and he speaks of his claim to the throne and his dissatisfaction with Henry’s rule. He knows he can’t make any moves yet, so he plans to side with Warwick and Salisbury.

Later, Gloucester speaks to his wife, the Duchess. He’s had a dream that his staff of office was broken. For her part, she dreamed about being crowned queen as Henry and Margaret bow before her. Gloucester warns her against excessive ambition. When he leaves, Hume enters, and the Duchess discusses her desire to hire a witch and a conjurer to summon a spirit that can foretell the future.

Petitioners come to court to ask for Gloucester’s help. They encounter Suffolk, and they mistake him for Gloucester. One petitioner, Peter, accuses his boss of saying York is the rightful king, and Suffolk sees he has found a way to weaken York. Henry and his court enter, discussing who should be the regent of France. Gloucester suggests York, but when Peter’s accusations cast doubt on York, he recommends Somerset instead. He then judges that the conflict between Peter and Horner should be decided by single combat. Meanwhile, Margaret expresses her frustration that Gloucester is still Lord Protector, since Henry is of age to rule.

Gloucester travels with the royal court to St. Albans. When he’s gone, the Duchess welcomes a witch and a conjurer to their home. They summon a spirit and ask the Duchess’s questions about Henry’s rule. The spirit gives ambiguous replies, then York, Suffolk, and Somerset enter and arrest the Duchess for dabbling in the occult.

At St. Albans, Henry and his queen and lords are hunting. Gloucester and Winchester follow along bickering. The company meets a formerly blind man who claims to have had his sight restored by miracle, but Gloucester sees he is lying and chases him away, “curing” his apparently disabled leg in the process. Buckingham then arrives with news of the Duchess’s arrest.

Back in London, York speaks to the earl of Salisbury and his son, the earl of Warwick, explaining the genealogical reasons for his claim to the throne. Both men believe him, call him the true king, and swear allegiance.

Having returned to London, Henry passes judgment on the Duchess and her coconspirators. She is to be banished to the Isle of Man. Gloucester affirms the justice of the king’s decision, but in his grief, he gives up his staff and his office. Then Peter and his master, Horner, enter for their combat. Peter is young and inexperienced in battle, but he manages to kill Horner, who shows up drunk. Later, Gloucester waits to see the Duchess paraded through the streets. She warns him that the lords are out to get him, but he insists that his honor will keep him from harm. He bids her farewell just as a messenger summons him to a meeting with the king.

Henry holds a meeting of the lords outside London, and Somerset arrives to report that all the French lands have been lost. Gloucester arrives, and Suffolk arrests him for treason. The lords all accuse him of wrongdoing. Henry says he hopes Gloucester can prove his innocence, but Gloucester says the lords have all plotted against him, and he will not be able to defend himself. Gloucester is taken away, and Henry mourns his inability to defend his innocent uncle against the plotting noblemen. He departs, and the other lords linger to come up with an excuse to kill Gloucester.

A messenger arrives with news of rebellion in Ireland, and York is dispatched with an army to quell the uprising. Left alone onstage, York revels in this turn of events. All he had lacked was an army, and now he has one. While he is in Ireland, he hires a rebel named Jack Cade to raise trouble in England. Cade bears a resemblance to York’s late uncle Mortimer, so the plan is for him to pretend to be a Mortimer and assert his claim to the throne. York wants to see what the public response will be to such a claim. If it’s positive, he will return and pursue the Crown.

Gloucester is killed by murderers at his home. Henry and his lords arrive for his trial, but Suffolk announces that Gloucester has died. Henry is distraught. Warwick and Salisbury enter with reports of unsettled commoners, who suspect Gloucester was murdered by Suffolk and Winchester. Examining the body, they decide that Gloucester died in struggle and was indeed murdered. The commoners demand the death or banishment of Suffolk. Henry grants their wish, and he orders Suffolk to leave the country. Left alone, Margaret and Suffolk declare their feelings for each other. Margaret then sends him away to France.

Meanwhile, Winchester has suddenly taken ill, and he dies miserably, raving in his bed. Suffolk is captured at sea on his way to France, and when he refuses to plead for his life, his captors behead him.

Cade speaks to his army of commoners, claiming to be the heir to the throne and promising a new England. He pledges to honor common labors and eliminate anyone who can read. Sir Humphrey Stafford and his brother arrive with an army to convince Cade and his men to lay down their arms, but the two armies come to blows. The Staffords are killed, and Cade drags their bodies to London.

Back at court, Margaret holds Suffolk’s head and mourns him. Henry listens to reports of Cade’s attack, and he determines to leave the city temporarily. Cade attacks London, hunting for and killing Lord Saye, whom Cade accuses of ruining England through literacy. Cade continues to wreak havoc on London until Buckingham and Clifford arrive and persuade the commoners to reassert their allegiance to the king. The rabble soon abandons Cade, and he flees. Just as Henry absolves the commoners of all guilt, he receives word that York’s army marches from Ireland. York claims that Somerset is a traitor, and he demands his imprisonment. Meanwhile, Cade is starving in the countryside, and he steals food from Alexander Iden’s garden. Iden arrives, the two come to blows, and Cade is killed.

York marches near London with his army. Buckingham arrives to ask about his intentions. York claims he only wants Somerset imprisoned. Buckingham says he has been, so York dismisses his army. Henry then enters, followed by Margaret and Somerset. Seeing Somerset free, York can contain himself no longer; he accuses Henry of being a weak, unfit king, and he declares himself to be the rightful heir to the throne. Somerset orders York’s arrest. York refuses to budge and asks for his sons, Edward and Richard, as well as the earls Salisbury and Warwick, to speak on his behalf. Salisbury and Warwick declare their allegiance to York. Henry agrees there is nothing left to do but fight.

Richard fights with Somerset and kills him. He then fights with Clifford and kills him. York’s army is winning, so Margaret urges Henry to retreat to London, where he has support. After the battle, York declares a tentative victory, and with his allies in tow, he prepares to enter London.