Verona, 18th century. A chorus tells of the endless feud between the Montague and Capulet families, and of the love of their children, Roméo and Juliette.
At a masked ball in the courtyard of the Capulet palace, Juliette’s cousin Tybalt assures Count Pâris that Juliette, who has been promised to him, will enchant him. Capulet presents his daughter to the guests and invites them to dance. Mercutio and Roméo, a Montague, have donned masks to sneak into the ball, together with other friends. Roméo tells them about a strange dream he has had, but Mercutio dismisses it as the work of the fairy Queen Mab. Roméo watches Juliette dance and instantly falls in love with her. Juliette explains to her nurse, Gertrude, that she has no interest in marriage, but when Roméo approaches her in a quiet moment, both feel that they are meant for each other. Just as they discover each other’s identities, Tybalt happens upon them and recognizes Roméo. Capulet prevents him from attacking Roméo, who, with his friends, beats a hasty retreat.
Later that night, Roméo enters the Capulets’ garden, looking for Juliette. When she steps out onto her balcony, he declares his love. Servants briefly interrupt their encounter. When they are alone once again, Juliette assures Roméo that she will be his forever.
Roméo visits Frère Laurent in his cell and confesses his love for Juliette. Shortly thereafter, she also appears with Gertrude. Hoping that their love might reconcile their families, Frère Laurent marries them.
Outside the Capulet palace, Roméo’s page, Stéphano, sings a song about a turtledove imprisoned in a nest of vultures. This angers several of the Capulets. Mercutio comes to Stéphano’s aid, but soon Tybalt challenges him to fight. Roméo steps between them and asks Tybalt to forget about the hatred between their families. Tybalt has nothing but scorn for him, and when he kills Mercutio in their duel, Roméo stabs Tybalt to death. The Duke of Verona appears and, after partisans of both families demand justice, exiles Roméo.
Roméo and Juliette have spent their secret wedding night in her room. She forgives him for killing Tybalt. The newlyweds passionately declare their love as day is dawning. They can hardly bring themselves to say goodbye. After Roméo has left, Capulet appears, together with Frère Laurent, and announces to his daughter that she is to marry Pâris that same day. Desperate, Juliette turns to Frère Laurent, who gives her a potion that will make her appear to be dead. He promises that she will awaken with Roméo beside her. Love lends Juliette courage: She overcomes her fear and drinks the poison. On the way to the chapel where her wedding to Pâris is to take place, Juliette collapses. To the guests’ horror, Capulet announces that she is dead.
Roméo arrives at the Capulets’ crypt. Discovering Juliette’s body, he believes her to be dead and drinks poison. At that moment, she awakens, and the lovers share a final dream of a future together. As Roméo grows weaker, Juliette takes a dagger from his belt and stabs herself. The lovers die praying for God’s forgiveness.