Later that afternoon, the afternoon of Romeo and Juliet's marriage, Benvolio and Mercutio are in the square. Benvolio tries to get Mercutio to go inside because itis hot out, the Capulets are out, and there is sure to be fight. Tybalt shows up and exchanges insults with Mercutio. Romeo shows up just as Tybalt and Mercutio are about to fight. Tybalt calls Romeo a villain. Romeo refuses to fight Tybalt, so Mercutio jumps in to defend his best friend. Romeo tries to break up the fight and Tybalt stabs Mercutio under Romeo's arm. Mercutio curses both the Montagues and the Capulets because their feud has led to his death. Romeo becomes enraged with grief and seeks revenge by killing Tybalt.
After slaying Tybalt, Romeo flees to Friar Laurence's cell. Benvolio tells the Prince what happened. Lady Capulet calls him a liar and demands that Romeo be killed. Lord Montague defends Romeo and says that he was just following the law by killing Tybalt, who had killed Mercutio (the Prince's cousin). The Prince has mercy on Romeo and exiles him instead of killing him. The Nurse goes home and tells Juliet what happened. At first, Juliet curses Romeo, but then she realizes that Tybalt would have killed Romeo if he hadn't killed Tybalt first. She sends the Nurse to Romeo with a ring, so he'll know she still loves him.
Romeo is in despair when Friar Laurence tells him of his exile. He does not think he can live without Juliet, you can see this when he says "There is no world outside Verona walls." The Friar admonishes Romeo for being so dramatic and for not appreciating the Prince's mercy. He tells Romeo to go to Mantua and hide out until things calm down and they can think of a way to bring him back to Verona. The Nurse arrives and gives Romeo the ring Juliet sent. He goes to be with Juliet for their wedding night, and the Friar reminds him to be gone before the morning watch is set.
Meanwhile, Paris has come to court Juliet. Her parents tell him that she is too sad about Tybalt to come downstairs to see him. He says that Tybalts death hasn't given him much of a chance to woo her. Lord Capulet offers to marry Juliet off to Paris in three days - leaving enough time between Tybalt's funeral and her wedding so people won't talk badly about the family. He says that he is sure that Juliet will do as he tells her to, and orders Lady Capulet to go up and tell Juliet the good news.
While all of this is taking place downstairs, Romeo and Juliet have been celebrating their wedding night upstairs. The two awake and Juliet tries to convince Romeo that it is still night and he doesn't have to leave. He tells her that he'd rather stay and die than have to leave her. Realizing the consequences, she tells him to hurry and go to Mantua. The Nurse barges in to warn them that Lady Capulet is on her way to the room. Romeo climbs back down the rope ladder, and Juliet has a bad vision that his is deathly pale and lying at the bottom of a tomb. He says that he has had the same vision, and it is sorrow that makes thems see these things. Then he flees to Mantua.
Juliet's mom comes into the room and tells Juliet that she will be married to Paris. Juliet refuses and her father threatens to throw her out into the street if she doesn't abide by his will. She asks the Nurse to give her advice, and the Nurse tells her to marry Paris, since Romeo has been banished. Juliet lies to the Nurse, telling her that she will go to confession and beg forgiveness for disobeying her father.