On the way home, Romeo chances upon his friend Mercutio arguing with Tybalt in the public square. Spying Romeo, Tybalt tries to taunt him into a fight. Romeo has no desire to harm the kinsman of his new wife. Mercutio is stunned and embarrassed by Romeo's soft words and draws his sword. Romeo tries to restrain his friend, but Tybalt thrusts his sword underneath Romeo's arm, stabbing Mercutio. Tybalt then flees with his friends. The wound is worse than at first suspected. "Ask for me tomorrow," says Mercutio, "and you shall find me a grave man." He dies.
Tybalt returns still cursing the unexpectedly reluctant Romeo. But Romeo is reluctant no longer, drawing his sword and slaying Tybalt. The moment Tybalt falls, Romeo realizes he has made a terrible mistake: "O, I am fortune's fool!"
Desperate, Romeo rushes to Friar Lawrence who advises him to travel to Mantua until things cool down. He promises to inform Juliet.
Juliet receives the news of Tybalt's death and Romeo's exile. She dares not mention her marriage to her father now. Then, she receives more bad news. Her father has decided it is time for her to marry. He has selected a suitor: Paris, a kinsman of Mercutio.
Juliet, too, rushes to Friar Lawrence for counsel. The good Friar launches an elaborate plot. Juliet should agree to marry Paris. She will then take a sleeping potion, which will simulate death for three days. Her body will be placed in a tomb while she is mourned, and the Friar will send word to Romeo. Romeo will arrive in time to rescue her. The celebration over her return to life will provide an opportunity to explain about the marriage and the circumstances surrounding Tybalt's death.
The plot proceeds according to plan, and the wedding preparations for Paris and Juliet give way to solemn funeral arrangements. But the Friar's letter to Romeo fails to reach him before he hears of Juliet's death. Romeo obtains a poison from an apothecary and travels to Verona.
Under the cover of darkness, he breaks into Juliet's tomb. They are alone for only a moment. Paris, who also had come to mourn Juliet, interrupts, and believing Romeo to be a grave robber, draws his sword. The two men fight, and Paris is killed. Dying, Paris asks that his body be placed next to Juliet's. Only now recognizing Paris, the guilt stricken Romeo obliges.
Then Romeo kisses the lips of his Juliet one last time.
Eyes, look your last.
Arms, take your last embrace.
And, lips, O you the doors of breath,
Seal with a righteous kiss
A dateless bargain to engrossing death
Romeo thanks the apothecary for his skill and drinks the poison.
The effects of the sleeping potion wear off, and Juliet awakens calling for Romeo. Finding him next to her, dead, with a cup in his hand, she guesses what has transpired. She tries to kiss the poison from his lips, but failing that, unsheathes his dagger and plunges it into her breast.
Friar Lawrence learns that Romeo has not received his letter and rushes to Juliet's tomb to rescue her. He discovers the tomb already open and finds the sad contents within. Soon the Friar is joined by the Night Watchman, who had been alerted to the disturbance. Then the families gather around the star-crossed lovers. The Friar's mournful account of their death shames the two families into ending their feud forever.