The play starts out in Algernon’s flat, which is richly and artistically decorated. Algernon is playing the piano while Lane prepares tea. Lane, when questioned by Algernon, claims he wasn’t listening to Alternon’s playing. Algernon claims he plays passionately rather than accurately.
Algernon accuses Lane of drinking eight bottles of champagne—which just happened to be consumed the night Algernon had Lord Shoreman and Mr. Worthing to dinner. Lane says the wine bachelor’s keep is superior to the wine in married households—and so servants can’t resist themselves. Lane believes marriage can be a pleasant state, despite the bad wine, though he hasn’t had much experience with it. Algernon isn’t interested in the details of Lane’s life and dismisses him, thinking how the lower orders are a bad example because of their lack of moral sense.
Ernest Worthing visits. He has been in the country visiting neighbors. He finds his neighbors in Shropshire so terrible that he refuses to speak to them. He notices the extra cups and little delicacies Algernon has at tea and assumes more guests are coming.
Algernon claims his Aunt Augusta and his cousin Gwendolen are coming. He doesn’t think Augusta will approve of Worthing being there because of his amorous attentions towards Gwendolen—which she reciprocates just as openly.
Worthing claims he plans to propose to her. Algernon thinks being in love is romantic, but romance ends with a proposal. The uncertainty is over, and thus so is the excitement. Worthing believes that idea is the cause for so many divorces.
Algernon doubts Gwendolen will marry Worthing. It is a rule with females never to marry a man they flirt with. He also doesn’t support the marriage to his cousin until Worthing resolves the matter with Cecily. Worthing claims he doesn’t know anyone by that name.
Algernon has Lane bring Worthing’s cigarette case, which he left behind when he dined last time. He tells Worthing he read the inscription written inside, which states it is a present from Cecily. Worthing claims it is his aunt but seems irritated. Algernon doubts that an aunt would use the phrase “From little Cecily with her fondest love.” Worthing claims not all aunts are tall.
Algernon, still refusing to give the cigarette case back, then continues reading the inscription. It calls Worthing “Uncle Jack.” An aunt wouldn’t call her nephew “uncle”, and she wouldn’t call him Jack when his name is Ernest.
Worthing says his name is Jack, at least in the country. He goes by Ernest in the city. He explains that he was adopted by Thomas Cardew as a boy. The man appointed him as guardian of his granddaughter Cecily. She calls him “uncle” out of respect. She lives with her governess at Jack’s country house. As a guardian, he has to behave very properly…but being proper is detrimental to health and happiness. He developed an alter ego named Ernest, which he tells everyone in the country is his younger brother.
Algernon claims he has also invented a relative by the name of Bunbury, who is an invalid. This invalid gives him an excuse to visit the country and also gives him an excuse to dine with friends when he is supposed to dine with his aunt.
Algernon believes dining with his aunt once a week is enough. She always treats him like a family member, neglecting to furnish him with female company. She always sits him next to a married woman who flirts with her husband.
Algernon wants to tell Worthing the rules about fake relatives, but Jack plans to kill his younger brother if Gwendolen accepts his proposal. Cecily is becoming too interested in Ernest. Algernon advises against killing Ernest. A person needs a fake relative if they are going to marry.
Aunt Augusta arrives. Algernon tells Worthing he’ll make sure he is alone with Gwendolen if Worthing agrees to dine with him later.
Aunt Augusta is cold towards Worthing. She explains they are late because they were visiting the recently widowed Lady Harbury, who looks much younger now that her husband is dead.
Algernon has eaten all the cucumber sandwiches, and Lane covers for him by saying there were no cucumbers.
Augusta tells Algernon she plans to have him visit Mary Farquhar, who is a very nice woman and a devoted wife. Algernon claims he cannot because he has just received a telegram from Mr. Bunbury. Augusta thinks Mr. Bunbury should make up his mind either to live or to die. People shouldn’t indulge invalids. She wishes Algernon to definitely come to her last reception on Saturday, and Algernon agrees.
Augusta and Algernon go into the music room. Worthing and Gwendolen remain behind. Worthing expresses his admiration of Gwendolen, and she claims she knew she was destined to be his because she loved his name—Ernest. This disturbs Worthing a bit, particularly when she claims she dislikes the name Jack…which is too plain.
Worthing proposes to her, and she accepts. Gwendolen informs her aunt of the engagement. Augusta tells her it is not something a girl arranges for herself and orders her to wait in the carriage.
Augusta stays behind to talk to Worthing. She tells him she doesn’t consider him an eligible choice, but she may change her mind if he answers some of her questions correctly.
She approves that he smokes. He is the right age. She is glad he is ignorant and not a know-it-all (those were the only two choices she gave him). She finds his income satisfactory. He tells her he has a country estate, and he lets his townhouse to an elderly lady. Augusta is disappointed he lives in an unfashionable side of town, but admits that can be altered.
They hit a snag when Worthing tells her he was adopted. He was given the name Worthing because that was Thomas Cardew’s destination when he found Jack in a handbag at the train station. Augusta finds this to be evidence of a bad family. Worthing claims he loves Gwendolen. Augusta tells him to produce some decent relations—and to acquire at least one parent.
Jack fumes to Algernon about Augusta. He plans to have Ernest die of apoplexy. Algernon advises changing the cause of death to a chill, for apoplexy is hereditary. Algernon asks if Jack has told Gwendolen about Cecily. Jack is certain they will be friends.
Gwendolen returns, wanting to talk to Jack. She tells Jack she’ll always be devoted to him, but she doubts her mother will allow her to marry him. She asks for the address of his country estate. Algernon copies it. She tells Jack that desperate action may be needed. Gwedolen leaves.