Don John has heard that Claudio and Hero are going to be married. Borachio proposes a plan to ruin it. Since he is a lover of Margaret, Hero’s chambermaid, he explains how he will arrange what looks like a meeting between Hero and a secret lover. First, he plans to have Don John warn Claudio and Don Pedro that Hero is a promiscuous young woman, and that it would be shameful for Claudio to marry her. After, he plans to lure them into witnessing a meeting at Hero’s window, where he and Margaret will appear, seeming to be Hero and another man. Don John agrees to the plan, and offers Borachio a thousand ducats to carry it out.
Don John decides on a scheme to ruin a marriage just one scene after Don Pedro decides on a scheme to create one. The rival schemes of the two brothers are parallel to their rivalry in war before the play begins. While the other tricks in the play are based on hearsay, Borachio’s plan is based on a misleading image. As Claudio says in the previous scene, people tend to trust their eyes.