The play opens as Algernon Moncrief plays the piano in his fashionable London flat, while his butler Lane prepares a tea service for Algernon’s Aunt Augusta, (Lady Bracknell), and her daughter, Gwendolen Fairfax, whom Algernon expects to arrive shortly. Surprisingly, Lane announces the arrival of Algernon’s friend Mr. Ernest Worthing (Jack).
Algernon greets his friend, who has been in the country. Jack discloses to Algernon that he has returned to town to propose to Gwendolen, whom he has been courting. Upon hearing this news Algernon confronts Jack about a woman named Cecily.
Jack initially denies the existence of this woman, but Algernon produces a cigarette case that he left behind the last time they dined together. The case is engraved with an inscription: “From little Cecily, with her fondest love to her dear Uncle Jack.” Faced with such evidence Jack comes clean, revealing that he has been leading a double life. Cecily is actually his ward. “Jack” is the name he goes by in the country, while “Ernest” is his alias in the city. He shares this name with his fictional brother, a mischievous character, whose scandalous lifestyle frequently calls Jack back to the city to straighten out his “brother’s” affairs. In reality, Jack uses “Ernest” as an excuse to escape his responsibilities in the country and pursue a life of pleasure in the city.
Jack’s charade confirms Algernon’s suspicion that his friend is a practiced “Bunburyist,” or a person who uses deception to shirk his duties. Algernon reveals that he is also an expert “Bunburyist,” having coined the term after his fictional, invalid friend, “Bunbury,” whose poor health frequently calls him to his so-called friend’s bedside.
Shortly thereafter, Lady Bracknell and Gwendolen arrive at Algernon’s flat. Algernon distracts Lady Bracknell, while Jack proposes to Gwendolen. She accepts on the account that she has always been enamored of the name “Ernest;” she makes it clear that she could never marry a man of any other name. This alarms Jack, whose composure becomes even more unsettled when Lady Bracknell bursts onto the scene, interrupting his proposal.
When Gwendolen announces her engagement, Lady Bracknell clears the room so that she can question Jack on his living arrangements, finances, and family relations. Upon learning that Jack has no parents and was adopted by Mr. Thomas Cardew, who found the infant Jack in a handbag left at a coatroom in Victoria station, she forbids Gwendolen from marrying Jack and leaves the flat in huff. Jack and Gwendolen bid each other adieu, while Algernon, intrigued by Jack’s young ward, makes plans to visit his friend “Bunbury.”
Act II begins at Jack’s country estate in Hertfordshire, where Miss Prism is failing to focus Cecily’s attention onto her German studies. The rector Dr. Chausible arrives and invites Miss Prism on a walk. While Cecily is alone, Merriman announces the arrival of Mr. Ernest Worthing. It is Algernon masquerading as Jack’s brother “Ernest,” but Cecily believes him to be the real deal. hortly thereafter, Jack arrives, dressed in mourning clothes, because his brother “Ernest” has just died. When Jack learns that Algernon is at the estate pretending to be “Ernest,” he is infuriated, but must keep up appearances so that his own lies and deceptions will not be revealed.
Meanwhile, Algernon, smitten by Cecily’s beauty and charm, proposes to her. She is not at all surprised because according to her diary they have been engaged for three months. She relates to him their love story and reveals that she has always dreamed of marrying a man named “Ernest.”
While Algernon rushes off to find Dr. Chausible, Gwendolen arrives to pay Jack an unexpected visit. Cecily invites her into the garden for tea, where she announces her engagement to Ernest Worthing, but Gwendolen counters that she is in fact Ernest’s fiancée. The ladies fling snide remarks at each other before Jack and Algernon arrive separately, each having gone to see Dr. Chausible about being christened “Ernest.”
The two women realize that Jack and Algernon have deceived them. They demand to know the whereabouts of the elusive “Ernest.” Jack reveals that “Ernest’” is not a real person, but a fiction, angering Cecily and Gwendolen even more.
In Act III Cecily and Gwendolen confront Jack and Algernon about their lies. Jack discloses that he assumed the name of “Ernest” so that he could visit Gwendolen often and Algernon admits that he pretended to be “Ernest” in order to meet Cecily. These explanations satisfy the two women, but they only fully forgive Jack and Algernon after the two men reveal that they are to be christened “Ernest” that afternoon.
Lady Bracknell breaks this moment of bliss by arriving to collect Gwendolen. Gwendolen reaffirms her engagement to Jack, while Algernon announces his engagement to Cecily. Lady Bracknell reiterates her disapproval of Jack and also objects to Cecily, until Jack reveals that Cecily is the heiress to a great fortune.
Interest piqued, Lady Bracknell advocates for Algernon’s engagement, but Jack, as Cecily’s ward, will not consent to the match until Lady Bracknell approves of his engagement to Gwendolen.
Lady Bracknell refuses, but turns her attention to Miss Prism, accusing her of losing her sister’s infant son twenty-eight years ago. Miss Prism confesses, explaining that she misplaced the boy in a handbag in a coatroom at Victoria station. Jack figures out that he was that abandoned child and presents the handbag as proof. Jack and ensemble turn to the manor’s library for verification finding an Army List that lists Jack’s father as “Mr. Ernest John Moncrief.” Jack’s real name is indeed Ernest; he has found a family name in Moncrief, a name and bloodline he shares with his real younger brother Algernon; and he has learned the “vital importance” of living up to his family name, as he embraces his betrothed.