Disturbed by Barnardine's unreadiness to die, the duke is relieved when the provost arrives with a solution. Another prisoner, similar to Claudio in coloring and age, has died of a fever. It is agreed that his head will be a substitute, and Barnardine will be hidden along with Claudio. When Isabella arrives, the disguised duke allows her to think that her brother's execution has gone forward. He tells her that the duke is returning and she must be present at the gates along with Angelo in order to reveal the truth and have her revenge. Lucio arrives, expressing honest grief at Claudio's death. Isabella departs, and Lucio attaches himself to the disguised duke, slandering the absent ruler as they leave together.
Escalus and Angelo are confused by the letters they have received from the duke, each contradictory. Now, on the verge of a return to the city, the duke sends word that they should meet him at the gates, giving advance notice that any with grievances should be there also. Angelo considers the possibility that Isabella may take this opportunity to accuse him but concludes that her shame and her inability to prove her claims will prevent her.
Giving some letters to Friar Peter, the duke asks him to deliver them and to call Flavius, Valentinus, Rowland, and Crassus to him. Varrius arrives as the friar is going off on his mission. The duke greets him and tells him other friends are expected, and the two walk off together.
Isabella describes to Mariana what the duke expects of them in the coming scene at the gates, and Friar Peter leads them away to accuse Angelo.
