It must have been a pleasant sight to see these old enemies converted into new and loving friends; and to behold their first meeting after being cheated into mutual liking by the merry artifice of the good-humoured prince.  But a sad reverse in the fortunes of Hero must now be thought of.  The morrow, which was to have been her wedding day, brought sorrow on the heart of Hero and her good father Leonato.

The prince had a half-brother, who came from the wars along with him to Messina.  This brother (his name was Don John) was a melancholy, discontented man, whose spirits seemed to labour in the contriving of villanies.  He hated the prince his brother, and he hated Claudio, because he was the prince’s friend, and determined to prevent Claudio’s marriage with Hero, only for the malicious pleasure of making Claudio and the prince unhappy:  for he knew the prince had set his heart upon this marriage, almost as much as Claudio himself:  and to effect this wicked purpose, he employed one Borachio, a man as bad as himself, whom he encouraged with the offer of a great reward.  This Borachio paid his court to Margaret, Hero’s attendant; and Don John, knowing this, prevailed upon him to make Margaret promise to talk with him from her lady’s chamber-window that night, after Hero was asleep, and also to dress herself in Hero’s clothes, the better to deceive Claudio into the belief that it was Hero; for that was the end he meant to compass by this wicked plot.

Don John then went to the prince and Claudio, and told them that Hero was an imprudent lady, and that she talked with men from her chamber-window at midnight.  Now this was the evening before the wedding, and he offered to take them that night, where they should themselves hear Hero discoursing with a man from her window; and they consented to go along with him, and Claudio said, “If I see any thing to-night why I should not marry her, to-morrow in the congregation, where I intended to wed her, there will I shame her.”  The prince also said, “And as I assisted you to obtain her, I will join with you to disgrace her.”

When Don John brought them near Hero’s chamber that night, they saw Borachio standing under the window, and they saw Margaret looking out of Hero’s window, and heard her talking with Borachio; and Margaret being dressed in the same clothes they had seen Hero wear, the prince and Claudio believed it was the lady Hero herself.

Nothing could equal the anger of Claudio, when he had made (as he thought) this discovery.  All his love for the innocent Hero was at once converted into hatred, and he resolved to expose her in the church, as he had said he would, the next day; and the prince agreed to this, thinking no punishment could be too severe for the naughty lady, who talked with a man from her window the very night before she was going to be married to the noble Claudio.

The next day, when they were all met to celebrate the marriage, and Claudio and Hero were standing before the priest, and the priest, or friar as he was called, was proceeding to pronounce the marriage-ceremony, Claudio, in the most passionate language, proclaimed the guilt of the blameless Hero, who, amazed at the strange words he uttered, said meekly, “Is my lord well, that he does speak so wide?”