Jack Worthing, who lives in the country, pretends to have a younger brother, Ernest, whose escapades frequently call Jack to London. Algernon Moncrieff pretends to have an invalid friend, “Bunbury,” whose attacks call Algernon into the country whenever there is a distasteful social function in prospect. This activity Algernon refers to as “Bunburying.”
Jack has managed to hide from Algernon the location of his country place and the existence of an attractive ward, Cecily Cardew. In Algernon’s bachelor flat at the tea hour, Jack confesses he has come to town to propose to Algernon’s cousin, Gwendolyn, who knows him as “Ernest.” Algernon refuses his help unless Jack explains the inscription on his cigarette case which Algernon has found. Thus Cecily’s existence is revealed, but Jack stubbornly refuses to reveal her whereabouts.
Gwendolyn accepts Jack, confessing she has always felt that a man named “Ernest” was her fate. During a subsequent catechism by Gwendolyn’s mother, Lady Bracknell, Jack gives his country address which Algernon takes down with the intention of going “Bunburying” during Jack’s absence from home. When Lady Bracknell learns that Jack’s identity dates from the discovery of a baby in a large black handbag in Victoria station she refuses to consent for the marriage.
Cecily, alone in the country with her governess, Miss Prism, is agreeably surprised at the appearance of Algernon in the guise of the much-discussed “Ernest.” The young couple lose no time in becoming engaged for, Cecily admits, the name “Ernest” has always fascinated her. When Jack returns unexpectedly to announce “Ernest’s” sudden death in Paris, he is disagreeably surprised to learn that “Ernest” is at the very moment in the house.
While Jack and Algernon are separately arranging with the rector for a rechristening, Gwendolyn arrives. The discovery of Gwendolyn and Cecily that they both seem to be engaged to “Ernest Worthing” results in a strained situation. The appearance of both young men clarifies the matter of engagements, but also reveals that neither is named “Ernest.” When the girls learn that their fiancés had been about to be rechristened for their sakes, they forgive the deception.
With the arrival of Lady Bracknell the question of consent again comes up. Lady Bracknell is quite willing that Algernon shall marry Cecily and her fortune. Jack, however, as Cecily’s guardian, refuses his consent unless Lady Bracknell permits his marriage to Gwendolyn. The appearance of Miss Prism who is recognized by Lady Bracknell, results in the identification of Jack Worthing as Algernon’s lost elder brother, Ernest, thus settling matters to everyone’s satisfaction.