Upon his entry, the duke finds Mariana at her home at Saint Luke's, listening to a boy singing a love ballad. Isabella soon arrives, and Mariana leaves the two to discuss their plans. She returns to meet Isabella and then goes aside with her while Isabella outlines the duke's idea of a substitute bed partner. Mariana agrees to the plan upon the duke's assurances of its propriety.
Given the choice of serving a prison term or becoming an executioner's assistant, Pompey chooses the latter, exiting with Abhorson to learn his new trade. The provost informs Claudio that he is to die on the following day, along with a condemned murderer. The duke arrives, expecting to hear of Claudio's pardon, only to be on hand as a letter is received from Angelo urging an early morning execution. The duke, however, persuades the provost to spare Claudio, sending the murderer's head in his place.
In his new trade as executioner, Pompey finds many of his former customers housed in the prison. At Abhorson's command, he calls Barnardine to be executed, but he refuses his execution. The duke enters and attempts to persuade Barnardine to accept his fate, but the prisoner merely reiterates his lordly refusal and returns to his cell.
