In a street outside Leonato’s house, the town policemen of Messina—collectively called the Watch—gather together to discuss their duties for the night. Dogberry, the head constable, and Verges, his deputy, command and govern them. Dogberry and Verges are well intentioned and take their jobs very seriously, but they are also ridiculous. Dogberry is a master of malapropisms, always getting his words just slightly wrong.

Under Dogberry, the Watch is very polite but not very effective at deterring crime. As Dogberry gives his orders to his men, it becomes clear that the Watch is charged with doing very little. For example, when asked how the men should react should someone refuse to stand in Don Pedro’s name, Dogberry replies, “Why then take no note of him, but let him go, and presently call the rest of the watch together, and thank God you are rid of a knave” (III.iii.25–27). Furthermore, the Watch is supposed to order drunkards to go home and sleep their drunkenness off—unless the drunkards won’t listen, in which case the men are to ignore them. The men are not to make too much noise in the street—they may sleep instead. They shouldn’t catch thieves, because it isn’t good for honest men to have too much to do with dishonest ones, and they should wake up the nurses of crying children—unless the nurses ignore them, in which case they should let the child wake the nurse by crying instead. In short, they may do anything they want and don’t have to do anything at all, as long as they are careful not to let the townspeople steal their spears.

Dogberry gives his men a final order: act particularly vigilant near the house of Leonato, for Leonato’s daughter, Hero, is to be married the next day, and the house is filled with commotion and chaos. After Dogberry and Verges depart, the men they have left behind sit down quietly on a bench and prepare to go to sleep.

Suddenly, the watchmen are interrupted by the entrance of Don John’s associates, Borachio and Conrad. Borachio, who does not see the watchmen, informs Conrad about what has happened this night. Acting on the plan he developed with Don John, Borachio made love to Margaret, Hero’s waiting maid, at the window of Hero’s room, with Margaret dressed in Hero’s clothing. Don Pedro and Claudio, who were hiding nearby with Don John, saw the whole thing and are now convinced that Hero has been disloyal to Claudio. Claudio, feeling heartbroken and betrayed, has vowed to take revenge upon Hero by publicly humiliating her at the wedding ceremony the next day. The watchmen, who have quietly listened to this whole secretive exchange, now reveal themselves and arrest Borachio and Conrade for “lechery,” by which they mean treachery. They haul them away to Dogberry and Verges for questioning.

Dogberry and Verges provide welcome comic relief amid Don John’s evil plotting. Their brand of humor is completely different from that provided by Benedick and Beatrice; while the two witty antagonists spar with a brilliant display of wit, Dogberry and Verges get half their words wrong, providing humor with their ignorance. Yet, like Benedick and Beatrice, they are in their own way good-hearted and sincere, and the humor of both duos, sophisticated and unsophisticated, hinges on punning and verbal display.

Borachio’s account of the events of that night inform us that Don John’s plans have been put into action and that everything is working out as he intended. Once again, however, we are faced with a disturbing element in this action: Claudio and Don Pedro both believe Don John’s claims and are willing to believe that they are watching Hero without investigating the matter more closely or interrogating Hero herself about it. When we see how ready Claudio is to believe that the woman he supposedly is in love with is betraying him, we are likely to be deeply troubled about him, even though we know that the play—being a comedy—has to end happily.

Borachio lists a few factors that might make the deception of Claudio and Don Pedro more understandable. He suggests that we should blame Don John’s “oaths,” which first made Don Pedro and Claudio suspicious of Hero’s guilt; the “dark night, which did deceive them” (III.iii.136–137); and Borachio’s own flat-out lies when he testified to them that he had made love to Hero. Some critics focus on the fact that Claudio is quite young and that he does not really know Hero very well as mitigating his distrust of her. Indeed, he seems hardly to have spoken any words to her before they become engaged, although presumably they have conversed more in the week that has passed since their betrothal. Nevertheless, Claudio’s swift anger and the terrible revenge he has vowed to take—shaming Hero in public and abandoning her at the altar—has remained troubling to generations of critics and readers, as has Don Pedro’s complicity in this desired revenge. Don Pedro, after all, does not have the excuse of youth and inexperience. The brutality of the principal male characters remains a problem with which readers of Much Ado About Nothing must grapple. It is difficult to feel sympathy for Claudio and Don Pedro after seeing how quickly they believe evil of Hero—and after what they do to her in Act IV, scene i, on the day of the wedding itself.