The Duke asks Claudio if he hopes to be pardoned by Angelo, and Claudio says that he still hopes he will be, but is ready to die. The Duke tries to resign him to death, saying that he should think of it as better than life. He describes how life is more frightening than death, because it has so many complications, and says that it is strange that we fear death more. Claudio thanks him and says that he is prepared to face death.
Isabella enters and says she wants to speak to her brother. The Duke asks the Provost to take him somewhere where he can hear their conversation without being seen. Claudio asks what happened, and Isabella tells him that there is no way for him to avoid death. Claudio asks if there is any way to change the sentence, and Isabella says that the only solution would require heartbreak. Claudio asks for more information, and Isabella tells him that Angelo has given him a way out of death which will imprison him for life. Claudio asks if the new sentence is life imprisonment, and Isabella says yes, only an imprisonment outside of jail.
Claudio asks for an explanation, and Isabella tells him that the punishment would be the loss of his honor. Claudio wants to know exactly what she means. Isabella evades the question, saying that she is afraid he would choose life. She tells him that death is more fearsome than painful, and that he should not think of it as a terrible thing. Claudio says that she thinks too little of him, and that he would embrace death if he had to. Isabella expresses her approval of this, saying that he is acting as their dead father would. She tells him that he must die because he is too noble to accept a shameful alternative.
Claudio curses Angelo, and Isabella agrees, finally telling him about Angelo's request. Claudio expresses his disgust, and then says, "Thou shalt not do't" (III.i.103). Isabella tells him that she would gladly give her life, but not her virginity. Claudio thanks her, and Isabella tells him to be ready to die tomorrow.
Claudio thinks about Angelo, wondering how he can have such desires and still enforce the law against them. He says that lechery is not a sin, or at least the mildest of the seven deadly sins. Isabella is surprised, and Claudio says, "Death is a fearful thing" (III.i.117). Isabella replies, "And shamed life a hateful" (III.i.118). Claudio describes a terrible view of death, and Isabella only says, "Alas, alas" (III.i.133).
Claudio changes his mind and asks his sister to give up her virginity for him, saying that a sin to save her brother's life would become a virtue. Isabella immediately grows angry, calling him a coward. She tells him that it is a kind of incest to require her to have sexual intercourse in order to save his life. Claudio tries to protest, but Isabella says that his sin was no accident, but a reflection of his general nature.