After a brawl between the rival families of Montague and Capulet (“Two households both alike in dignity”), the Prince threatens with death anyone who “disturbs our streets again”. Romeo, Montague’s heir, masked at a Capulet’s dance, becomes infatuated with Capulet’s daughter, Juliet. From the garden (Act II) he overhears her avowal (“Take all myself”) as she stands on her balcony and their love scene follows (II.2). Next afternoon Friar Lawrence marries them in secret.
When (Act III) Romeo refuses to fight with Tybalt, a passionate Capulet (who is now his cousin by marriage), the gallant Mercutio takes the challenge himself. He is killed by mischance, and Romeo, enraged, kills Tybalt. In his absence the Prince banishes him; the Friar tells him to stay the night with Juliet and then wait in Mantua until recall is possible (III.3). When Juliet’s father insists that she shall marry a young nobleman, Paris, and she gets no aid from either her mother or her nurse, the Friar (Act IV) gives her an opiate (to take on the following night) that will put her in a death-like trance for “two-and-forty hours”. She will be laid in the Capulet vault; when she wakes, Romeo will be there.
Juliet is duly placed in the vault as dead, but the Friars’ messenger to Mantua miscarries; hearing only of Juliet’s “death” (“Then I defy you, stars!”, Act V), Rome o hastens to the tomb at night and is surprised by Paris whom he kills; in the vault he drinks poison he was bought from a Mantuan apothecary, and dies by Juliet’s side. She wakes as the desperate Friar enters, and on seeing Romeo dead, stabs herself. The Prince and the heads of the families are roused; over the bodies of their children Capulet and Montague are reconciled, and the Prince closes the play: “For never was a story of more woe/Than this of Juliet and her Romeo.”
-from The Pocket Companion to Shakespeare’s Plays by J.C. Trewin