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.