Mrs. Harrel has a masquerade ball. Mr. Monckton is in disguise as a black demon and fights anyone who comes near Cecelia.. A person dressed like a white domino tries to help her, as do Mr. Arnott, Mr. Gosport, and Mr. Belfield. Cecilia is surprised at how well the domino knows the faults of her guardians. She wonders who he could be. Later, Cecelia goes to the opera again with Mrs. Harrel. There, she meets Mr. Belfield, who is courteous; but Sir Floyer acts rudely. The two men get angry and have an argument that leads to a duel. Afraid, Cecilia hurries to her house, and worries over the duel.