Sibyl Vane is exclaiming to her mother about how much in love she is with her Prince Charming, as she calls Dorian Gray, not knowing yet what his name is. Her mother warns her that she must keep her focus on acting since they owe Mr. Isaacs fifty pounds. Sibyl is impatient with her mother and tries to get her mother to remember when she was young and in love with Sibyl's father. Her mother looks pained and Sibyl apologizes for bringing up a painful subject.
Her brother Jim comes in. It's his last night on shore. He is booked as a sailor on a ship headed for Australia. When Sibyl leaves the room, he asks his mother about the gentleman he has heard has been coming to the theater to see Sibyl every night. His mother tells him the man is wealthy and it might be a good thing for Sibyl. Jim is not convinced.
When Sibyl comes back, she and Jim go for a walk in the park together. While there, Jim questions her about the man who has been calling on her. She only says how much she is in love with the man and how she is sure he's trustworthy. Jim says that if he comes back and finds that the man has hurt her, he'll kill the man. They walk on and return home after a while.
Alone again with his mother, Jim asks her if she was married to his father. She has been feeling like he has been on the verge of asking this question for weeks. She is relieved to get it out in the open. She says she was never married to the man. He was married, but loved her very much. He would have provided for her and her family, but died. Jim tells her to keep the gentleman away from Sibyl. She tells him that he need not worry because Sibyl has a mother, but she herself didn't. He is touched by her sincerity and they embrace. Soon, though, he has to get ready to leave for his ship. Mrs. Vane thinks about his threat to kill Sibyl's Prince Charming, but thinks nothing will ever come of it.
This chapter takes the reader to an entirely different social scene. The world of the Vanes. It serves to humanize Sibyl for the reader by showing her in her roles as daughter and sister. She is innocent as Dorian told Lord Henry she was. She knows nothing of the position which her social class puts her in relation to Dorian Gray. Her brother and her mother do know. For her brother, she will be used and discarded by a rich man. For her mother, she might be lucky enough to get money out of the rich man before he gets tired of her. The chapter closes with the revelation that James and Sibyl's father was an aristocrat himself and that their parents never married.
Lord Henry greets Basil Hallward as he arrives at the Bristol for dinner. He tells him the news about Dorian's engagement to Sibyl Vane. Basil is surprised and can't believe it's true. He can't believe Dorian would do something as foolish as to marry an actress in light of his "birth, and position, and wealth." Lord Henry acts nonchalant about the news and Basil is quite worried.
Finally Dorian arrives elated to tell the others of his news. Over dinner he tells them that he proposed to Sibyl on the previous evening after watching her as Rosalind. He kissed her and told her he loved her and she told him she wasn't good enough to be his wife. They are keeping their engagement a secret from her mother. Dorian tells Lord Henry that she will save him from Lord Henry's "wrong, fascinating, poisonous, delightful theories" about life, love, and pleasure. Lord Henry says they aren't his theories but Nature's. Basil Hallward begins to think the engagement will be a good thing for Dorian after all.
As they leave, Lord Henry tells Hallward to take a separate conveyance to the theater since his is large enough only for him and Dorian. As he rides in the carriage behind Lord Henry's, Basil Hallward feels a strong sense of loss, as if Dorian Gray will never again be to him all that he had been in the past. He realizes that life has come between them. He feels, when he arrives at the theater, that he has grown years older.
This chapter plays a structural role in the plot, brining the three men back together before their parting again to go their own ways. Basil seems out of the loop of Dorian's affections almost completely. This status is underlined as he is told to take his own conveyance to the theater alone while Dorian rides with Lord Henry. The engagement to Sibyl seems to be Dorian's last hope of regaining the innocence of youth which he has lost to Lord Henry's theories.