Dr. Chasuble arrives and announces that he is ready for the christenings. Jack replies that they are useless now, and Chasuble decides to head back to the church where Miss Prism is waiting. The name Prism shocks Lady Bracknell, and she demands to see the governess. When Miss Prism arrives, she sees Lady Bracknell and turns pale. In a moment of great coincidence, Lady Bracknell reveals that Miss Prism left Lord Bracknell's house 28 years ago. On a normal walk with the baby carriage, she disappeared, along with the baby. She demands to know where the baby is. Prism explains that in a moment of great distraction, she placed the baby in her handbag and her three-volume, manuscript in the baby carriage. The baby and handbag were accidentally left in the train station. When she discovered her error, she abandoned the baby carriage and disappeared. Jack excitedly asks her which station it was, and when she reveals that it was Victoria Station, the Brighton Line, he runs from the room and returns with a black leather bag. When Prism identifies it, he embraces her, believing her to be his mother. She protests that she is not married and says that he will have to ask Lady Bracknell for the identity of his mother.
Jack discovers that he is actually the son of Lady Bracknell's sister, Mrs. Moncrieff, and that Algy is his older brother. Jack is overcome to know that he really does have an unfortunate scoundrel for a brother. He asks what his christened name was, and Lady Bracknell explains that it is Ernest John. So, Jack asserts that he had been speaking the truth all along: His name is Ernest, and he does have a brother. Both couples embrace, as do Chasuble and Miss Prism, and Jack declares that he finally realizes the importance of being earnest.
