But, the Duke proclaims that Angelo must die for committing the same sin as Claudio; Mariana protests this decision, and Isabella's intervention, to ask that Angelo be allowed the mercy her brother did not get, then causes the Duke to let Angelo go.
Claudio is fetched from the prison, and the fact that he is alive is revealed to all.
He does this for no reason other to have her be very happy, and perhaps look even more just and heroic, when it is revealed that he actually saved Claudio's life.
The Duke did his duty as a ruler, seeing to it that justice was kept and no undue sentence performed; however, through this public performance of accusation, repentance, and grief, he shows the extent of his power, and makes himself look even more just, important, and beneficent since he appears to have single-handedly acquired justice for everyone.
Angelo warns the Duke that he fears her wits are not about her; but, Isabella accuses Angelo anyway, of being "an hypocrite, a virgin-violator" before the Duke and his company.
She says that he appears good, but is notand that her claims must not be dismissed, but heeded with all possible caution.Isabella is allowed to speak her tale, and tells of how she went to Angelo to plead for her brother's life, and had to sleep with Angelo to get him released, although he was executed anyway.The Duke, of course, along with Friar Peter, make a show of not believing her, and say that Angelo is too good by reputation for these allegations to have any weight with them.Angelo decides that he wants to figure out the whole truth of what is going on; Friar Peter is sent to fetch "Friar Ludovico," the Duke in disguise, as he will be the key witness to what actually went on with Angelo and the two women. The Provost and Isabella come with him, as he starts to testify as to his part in the whole matter.The Duke acts rather scurrilous as the friar, so much so that he is almost dragged off to prison before he can give any kind of testimony at all.The Duke's statement that Angelo's "desert speaks loud," and should have "a forted residence 'gainst the tooth of time" is especially ironic; for Angelo's desert is non-existent, and has already been corrupted, not by time but by lust. The Duke plays his part, acting like he is ignorant of the recent goings-on in the town; Isabella plays the part of a wronged woman with great dramatic skill.All that has been pre-arranged and staged by the Duke is being executed before his eyes; his manipulations are being acted out in a public place, to the end results that the Duke wantsjustice, and Angelo's exposure. reality to the assembled party; she makes the good point that anyone can appear to be just, but can be completely corrupt within, as Angelo is.Isabella then kneels before the Duke, and asks to be heard so that she can claim justice.The Duke urges her to speak, and to address Angelo with her grievance, since he is one that can give justice to her.Friar Peter has Mariana come forward, as the Duke urges Angelo to be judge of his own case.Mariana says she will not show her face until her husband bids her to do so; she says she is not a maid, a widow, or a wife, and then tells them that she has slept with her husband, whom Isabella is accusing.