Off the coast of England, an English ship is under attack. On board are the Captain and the master and mate, Walter Whitmore. Their prisoners include a disguised Suffolk and two gentlemen. The Captain shares out the prisoners among the master, mate, and Whitmore, giving Suffolk to Whitmore. Each gentleman asks what his ransom shall be. The gentlemen offer to send for the money. Suffolk starts when he hears his captor's name is Whitmore; once an astrologer had foreseen his death would come with a man named Whitmore, and he already had heard he might die at sea.
Suffolk reveals his identity and declares that his honorable blood must not be shed by someone so lowly as Whitmore or the Captain. Such men are only fit to serve such nobles as himself, he declares. The Captain, annoyed, orders Suffolk to be taken away and beheaded. The Captain scorns Suffolk for his behavior, for having kissed the queen, delighted in the downfall of Gloucester, and for daring to scheme to wed the king to the daughter of a worthless noble of France. The Captain accuses Suffolk of losing Anjou and Maine and further encouraging the house of York to rise up against the king. Suffolk insists that it is impossible that he should die at the hands of someone so lowly, but Whitmore is determined. The gentlemen urge him to beg for his life, but Suffolk says he is unused to begging, and he would rather stoop to have his head chopped off than bow to any save the king. He is a real noble and, thus, exempt from fear, he says; sometimes great men die at the hands of low men. Whitmore leads him off and returns with his head. One of the gentlemen determines to carry the body to the king.
Meanwhile, on land, Rebels overrun the land, discussing Jack Cade's plans for the kingdom. Artisans will not be in favor in the new regime, they agree, and only workmen will be honored. Then, Cade enters with the Butcher and the Weaver. Cade makes a speech, announcing his alleged lineage through the Mortimer and Plantagenet family. After each point, the Butcher mocks him to the rebels, saying Cade is as far from nobility as one can get. Cade announces that when he is king, beer will be plentiful, there will be no money, and the first thing they will do is kill all the lawyers and punish all those who are able to read. Just then a clerk is brought in; Cade asks if the man can read and write, and when he answers affirmatively, Cade orders him to be hanged with his pen and inkhorn around his neck.
A messenger enters to tell of an attack by Stafford and his brother. Cade says Stafford isn't too scary, he is just a knight, and proceeds to knight himself. Stafford enters and demands the rebels lay down their arms. Cade says he is the rightful heir to the throne, and they debate the point. Stafford's brother accuses Cade of having learned his argument about the line to the throne from York, but Cade denies it. Cade and the Butcher say they mean to kill the Lord Saye, who sold Maine to the French and weakened the English holdings in France.
Stafford and his brother agree there's no negotiating with Cade, so they decide to send the king's troops against them and proclaim Cade's followers to be traitors. Cade calls to those who love the commoners to follow him and to hunt the lords in the name of liberty. The Butcher is frightened by the orderly rows of soldiers approaching, but Cade declares his army to be most in order when they are most disorderly. In the ensuing battle, both Staffords are slain, and Cade's army marches toward London.
In London, Henry enters reading the rebels' supplication, Margaret enters with Suffolk's head, followed by Buckingham, Lord Saye, and others. Margaret is distraught but tries to think of revenge instead of sadness. Henry tells Saye that the rebels want his head. Then, he notices that Margaret is still mourning, and he comments that she wouldn't have mourned so much if he had died. A messenger enters to tell of the approach of Cade's army and how Cade calls himself Mortimer and vows to become king. Buckingham advises the king to leave London; the king suggests Saye come, too, but since he might endanger the king, Saye decides to stay in London. Another messenger enters, saying Cade is nearly at London Bridge, and all the citizens join his march. Henry and Margaret flee, and Buckingham advises Saye to be brave. Saye says he is innocent, so, therefore, he is brave.
A lord in the Tower asks citizens below if Cade has been killed yet. They report that the mayor of London has called for reinforcements, so the lord sends them. But Cade and his men invade London and take the city. Cade kills a messenger who arrives with a note saying that an army gathers outside town to oppose him. Cade and his troops head out to fight.
These scenes, mostly very short and filled with stage directions, encompass most of the action of the play. Suffolk dies at sea, as was predicted. He seems most upset that he would be killed by men he deems lowly. Yet as lowly as they are, the Captain has a clear understanding of everything Suffolk has done against the kingdom, and he enumerates Suffolk's faults before ordering his head chopped off. Even as Suffolk scorns the regular people, they nevertheless seem to be far more aware of the machinations of the nobles than are the other members of the royal court.
Meanwhile, Cade's attack against the king begins. York intended Cade's actions as a test to see how the commoners liked the idea of a York as king; the commoners are enthusiastic, though they do not seem to believe for a moment that Cade is actually a Mortimer in line to the throne. They make fun of his speeches about the throne and kingdom, and they cheer on his declarations about what he will do when he is a king, including creating a realm where the simplest working man is the most honored, and literate people will be executed. Mostly they seem interested in creating trouble, and they aren't that interested in whether Cade becomes king. Some of Cade's declarations, about making the common working man the most important and banning literacy, reflect some of the rhetoric of rebel leaders of the time, including a tradition of popular radicalism that championed laborers. Yet while Cade offers an egalitarian vision, where there is no money and everyone will become more or less equal, he still declares he will become the king.
The reason that the rebels want Lord Saye is unclear, especially since he is accused of having lost Maine, when it was Suffolk who negotiated the exchange of Anjou and Maine for Margaret. But since Suffolk was dead, perhaps the rebels needed another scapegoat.