The next morning, the Duke's mistress tells him that she has found out that the rebels have planted a spy at the Duke and Duchess's house. The Duke is furious, but he is not angry because the spy has saved his life. He is furious because the Duke has told him about his family, and he does not think the spy can be the one who has planted the spy in his house. He tells the mistress that he has known the Duke since they were ten years old, and they have known each other for the past hour. The mistress tells the Duke that she found out about the spy at his house an hour ago, and she knows how to test the identity of the spy. She says that if the spy tells her that he is with the rebels, then she can be sure it is him.