Polly goes to visit Lucy at the jail (Lucy lives there because she is Brown’s daughter). Polly starts by apologizing for the way she behaved the day before. She explains that she was upset by Macheath’s behavior and that Lucy should tell him that when she sees him. Lucy says that she will not be seeing him. Polly is surprised and says perhaps he is avoiding Lucy because she loves him too much. They agree that perhaps both of them are too deeply in love with him.
Polly then explains how she came to be married to Macheath. She tells Lucy that he took her to a hotel and how Polly never would have expected to be married twelve days ago. She then asks Lucy why Macheath behaved so coldly to Polly the day before. Lucy says that maybe Macheath is not to blame and suggests that perhaps Polly should have married someone of her own class. Polly considers this suggestion, then begins to weep. This outburst finally prompts some sympathy from Lucy, who tells Polly that at least she can take consolation in being his wife on paper. She goes to fetch something for Polly to eat.
As soon as she steps out, Polly hisses an aside to the audience, calling Lucy a “silly little fool.” Lucy returns, and Polly asks about a picture of Macheath and questions whether Macheath brought it there. Lucy says he has never been in this room, and now she realizes that Polly has come to find out where Macheath is. She calls Polly out on her sneaky plan, but Polly demands to know where he is. Lucy says she has no idea. Polly is delighted to learn that Lucy is in the dark as well and bursts out laughing while Lucy begins to weep. Polly now offers Lucy her own food and consoles her. Despondent, Lucy reveals that her pregnancy is fake, and Polly laughs even more. She calls Lucy a fool to her face.
Just then, Lucy looks out the window and sees that Macheath has been captured again. Polly collapses in despair. Mrs. Peachum enters with a widow’s dress for Polly and insists that she put it on. She tells Polly that she will make a lovely widow if only she will cheer up a little.
The interaction between Lucy and Polly in this scene reiterates that even relationships are motivated by self-interest in the play. The scene is built on the conflict between two women who want the same man and who are willing to descend to the depths of cruelty to get him. Polly and Lucy get pleasure from the other’s misery. The reversal in their roles, from Lucy laughing while Polly weeps to Lucy weeping while Polly laughs, has a pleasing symmetry, but the essence of the scene is cruelty. The only reason they are nice to one another is to find out more information about Macheath’s current location. As the scene begins, Polly does not announce her goal. Instead she makes what appears to be idle conversation to try to trick Lucy into revealing Macheath’s whereabouts. Similarly, Lucy is suspicious of Polly’s purpose in visiting but remains polite until Polly’s motive is revealed. Once that goal is exposed, the scene takes a dramatic shift. Polly, who seems like a sweet girl, now displays her own self-interest by demanding to know where Macheath is and does not care if she hurts Lucy in the process.
The scene also offers a measure of advancement in the character of Polly. Polly is the only character in the play that truly changes because she is motivated by both love and self-interest. This capacity for love hits Polly when Macheath arrives at the jail and she collapses. Her life is still inextricably bound to his through her love, even though she can also be cold-hearted and cruel to Lucy. Here the audience sees that her motivation to locate Macheath does not necessarily make her a kind person and that she has also coarsened over the course of the play. She is no longer just a naïve and youthful girl madly in love. Like Lucy, Polly demands what she believes is hers—that is, the man she loves. She claims that Macheath is her husband. Polly’s apology to Lucy is only used as a means of finding her love. Macheath’s rejection and her gradual introduction into this world of crime have made her willing to be ruthless. Polly will also be cruel if this behavior will help bring her closer to Macheath, and she takes great pleasure in Lucy’s despair after she tells her that Macheath has left both of them behind.