Don Pedro and his regiment are returning to Messina from the wars and are welcomed by Leonato, the governor of the city.
Among Don Pedro's men are his malcontent brother Don John, to whom he has only recently been reconciled, young Count Claudio from Florence, who has acquired something of a reputation for bravery in war, and Benedick, a gentleman of Padua.
Benedick is a confirmed bachelor. Beatrice, Leonato's lively niece, declares herself equally determined to remain unmarried. These two are a match for each other's wit and when they meet, they immediately resume their sparring.
Young Claudio, on the other hand, has fallen in love with Leonato's daughter Hero. When Don Pedro offers to court her on his behalf at a party that night, Claudio gladly agrees. Their marriage is soon being arranged.
The resentful Don John, however, is looking for an opportunity to get back at Claudio and his brother. His companion Borachio presents John with a plan. He will persuade his girlfriend Margaret, Hero's waiting woman, to dress up in her mistress's clothes and be seen with him at the window. Claudio and Don Pedro, brought along to witness this, will draw the obvious conclusion and assume Hero is entertaining a lover.
Meanwhile, the friends of Beatrice and Benedick conspire to trick them both into believing that each loves the other. Their behaviour undergoes a remarkable change.
Borachio and Conrade are arrested by the local watch, who overhear them discussing the plot to deceive Claudio, but this doesn't come to light in time to prevent Claudio being taken in by it. On his wedding day he denounces Hero as a whore. She faints and is believed dead.
The friar who was to have married them proposes that it be given that our Hero is indeed dead, and she should be kept hidden until the truth be known and in the hope that Claudio will eventually repent his hasty action. Beatrice, enraged by Claudio's behaviour, urges Benedick to challenge him to a duel.
Brought before Don Pedro by Constable Dogberry, Borachio confesses his part in the plot. Leonato proposes that the now penitent Claudio should marry his niece, said to be the image of the dead Hero, and Claudio readily agrees.
