The play opens with Vincentio, the benevolent duke of Vienna, commissioning his deputy Angelo to govern the city while he travels to Poland. In actuality, the duke remains in Vienna disguised as a friar in order to watch what unfolds. Following the letter of the law, Angelo passes the death sentence on Claudio, a nobleman convicted for impregnating his betrothed, Juliet. Claudio's sister Isabella, a novice in a nunnery, pleads his case to Angelo. This new deputy ruler, a man of stern and rigorous self-control, finds to his consternation and amazement that he lusts after Isabella; her virgin purity awakens in him a desire that more profligate sexual opportunities could not. Hating himself for doing so, he offers to spare Claudio's life if Isabella will have sex with him. She refuses and is further outraged when her brother begs her to reconsider.