The families of Montague and Capulet use any excuse to publicly fight in the streets of Verona, drawing a strict rebuke from the Prince (Stellan Skarsgård). But young Romeo (Douglas Booth) of the Montagues is not interested – he is far too in love with Rosaline, a cousin to the Capulets, a romance which his cousin Benvolio (Kodi Smit-McPhee) urges him not to pursue.
But that night, there is to be a masked celebration at the Capulet estate, and Romeo manages to secure an invitation. The Capulet household prepares for the event, where Lord and Lady Capulet (Damian Lewis, Natascha McElhone) hope that their daughter Juliet (Hailee Steinfeld) will accept the advances of young Count Paris (Tom Wisdom). A free spirit little interested in romance, Juliet seems more interested in bantering with her nurse (Lesley Manville) than listening to her parents.
At the ball, Romeo instantly forgets his feelings for Rosaline when he spies Juliet; she is likewise struck dumb when she sees Romeo. They dance briefly, noted by Juliet’s cousin Tybalt (Ed Westwick), who is told by Lord Capulet to let them be and not start trouble. Later, Romeo and Juliet are dismayed to learn that their new loves are of the rival family; undaunted, Romeo spies Juliet on her balcony and boldly declares his love for her.
With the help of Friar Laurence (Paul Giamatti), Romeo tries to conspire a way to pursue Juliet without incurring the wrath of his family, while Juliet relies on her nurse to discreetly deliver messages to her love. But the bad blood between the two families is too strong: in a street duel, an angry Tybalt slays Romeo’s beloved kinsman Mercutio (Christian Cooke).
Romeo, his passions unchecked, then kills Tybalt. Hoping to put an end to the blood feud, the Prince banishes Romeo from Verona – but this is worse than death, because he will forever be separated from Juliet.
As the lovers grow more desperate, Friar Laurence attempts to hatch a plan that will allow them to be together forever – but will their boldness and bravery in love result in eternal happiness or tragedy?