A plot is planned to keep Claudio and Hero from marriage. Who plans it and what will it be? (Act 2, not sure what scene)

Don John is furious over the fact that Claudio is marrying Hero. Borachio, his friend, offers to thwart the marriage. He tells Don John that he is a good friend of Hero's servant-gentlewoman Margaret and that he can get her to look out at Hero's chamber window. Borachio proposes that Don John get Don Pedro and Claudio to watch the chamber window at an appointed time, and he will then meet Margaret in the room, thereby making them think that Hero has another lover. Don John promises Borachio a thousand ducats if the plan succeeds.