Dogberry and Verges, both fools in charge of the watchmen, get one of their men and make him the constable of the watch for the night. He agrees, but asks what he should do if he orders a man to stop and the man refuses. Dogberry tells him to ignore the man, and good riddance of a knave, because they can only stop loyal subjects of the Prince. Verges then orders the man to keep silence throughout the town. They leave the man to his job as constable, and Dogberry orders him to wake him up only if something important comes up.
Borachio and Conrad arrive and accidentally stand within hearing distance of the watchman whom Dogberry appointed constable. Borachio tells Conrad that he earned a thousand ducats from Don John that night because he wooed Margaret in Hero's room and called her Hero. Meanwhile, Don John had brought Don Pedro and Claudio to orchard where they watched this whole scene and became convinced that Hero was committing infidelity.
One of the night watchmen, having overheard this story, arrests Borachio and Conrad for villainy. They agree to go peacefully and are taken to be judicially interrogated.