Leonato, Governor of Messina and a powerful landowner, hosts Don Pedro at his lavish estate, which he shares with his lovely daughter Hero, his witty niece Beatrice and his elderly brother Antonio. Don Pedro has just returned from a victorious military campaign with his rebellious brother, Don John, in tow. Returning with Pedro are his soldiers and good friends Claudio, a well-respected young nobleman of whom Don John is bitterly resentful, and Benedick, a confirmed bachelor engaged in an ongoing feud with Beatrice, also resolutely single.
When the soldiers arrive at Leonato’s estate, Claudio falls in love with Hero and asks Don Pedro to help him win her hand, and Beatrice and Benedick resume their war of wits with a skirmish of insults. At a masked ball that evening, Don John convinces Claudio that Don Pedro is wooing Hero for himself. A jealous Claudio confronts Don Pedro, but the confusion is sorted out and Claudio and Hero are betrothed. Meanwhile, after a particularly charged sparring match between Beatrice and Benedick, Don Pedro suggests a plan to the happy Claudio and Hero. The three of them will trick Beatrice and Benedick into falling in love with each other.
The next day, Don Pedro, Claudio and Leonato ensure that Benedick (hidden in a garden arbor) overhears them discussing Beatrice’s presumably passionate love for him. Hero and Ursula, her gentlewoman, play a similar trick on the eavesdropping Beatrice. Meanwhile, Don John plots against Hero and Claudio. He arranges for his companion, Borachio, to make love to Margaret, Hero’s attendant, at Hero’s window on the eve of the wedding and brings Don Pedro and Claudio to watch. The plot works, but Constable Dogberry’s men hear a drunken Borachio boasting of his role in the plot and arrest him.
Believing he has seen her being unfaithful to him, the enraged Claudio humiliates Hero and denounces her at the altar. Hero faints and is left for dead. Friar Francis, skeptical of Claudio’s accusation, proposes that Hero lie low until the truth is revealed and enlists the aid of Leonato, who tells the soldiers that his daughter has died from grief. In the aftermath of the abandoned ceremony, Beatrice and Benedick finally confess their love to one another. Beatrice demands that Benedick prove his love by killing Claudio.
Benedick challenges Claudio to a duel, but Dogberry brings in Borachio, who reveals Don John’s plot. With Borachio’s confession, Hero is exonerated and Leonato demands a public apology from Claudio. In penance for causing Hero’s alleged death, Claudio agrees to marry Leonato’s hitherto unseen niece—only to discover, when he unveils his bride, that she is Hero. Beatrice and Benedick agree to wed alongside them as news comes that Don John has been taken prisoner.