Act IV opens with Gerald writing a letter in his mother's sitting room, the contents of which will ask his father to marry Mrs. Arbuthnot. Lady Hunstanton and Mrs. Allonby are shown in, intending to visit Mrs. Arbuthnot. The two comment on her apparent good taste and soon leave when the maid tells them that Mrs. Arbuthnot has a headache and will not be able to see anyone. Gerald says that he has given up on being his father's secretary, and he has sent for Lord Illingworth to come to his mother's estate at 4 o'clock to ask for her hand in marriage. When Mrs. Arbuthnot enters, Gerald tells her all that he has done and that he will not be his father's secretary. Mrs. Arbuthnot exclaims that his father must not enter her house, and the two argue over her marrying Gerald's father. Gerald claims that the marriage is her duty, while Mrs. Arbuthnot retains her integrity, saying that she will not make a mockery of marriage by marrying a man she despises. She also tells of how she devoted herself to the dishonor of being a single mother and has given her life to take care of her son. Hester overhears this conversation and runs to Mrs. Arbuthnot. Hester says she has realized that the law of God is love and offers to use her wealth to take care of the man she loves and the mother she never had. After ensuring that Mrs. Arbuthnot must live with them, Gerald and Hester leave to sit in the garden.