The play is set in "The Present", which was 1895 at the time.[70]
Act I: Algernon Moncrieff's flat in Half Moon Street, West
The play opens with Algernon Moncrieff, an idle young gentleman, receiving his best friend, Jack Worthing ('Ernest'). Ernest has come from the country to propose to Algernon's cousin, Gwendolen Fairfax. Algernon refuses to consent until Ernest explains why his cigarette case bears the inscription, "From little Cecily, with her fondest love to her dear uncle Jack." 'Ernest' is forced to admit to living a double life. In the country, he assumes a serious attitude for the benefit of his young ward, the heiress Cecily Cardew, and goes by the name of Jack, while pretending that he must worry about a wastrel younger brother in London, named 'Ernest.' Meanwhile, he assumes the identity of the libertine Ernest in the city. Algernon confesses a similar deception: He pretends to have an invalid friend named 'Bunbury' in the country, whom he can "visit" whenever he wishes to avoid an unwelcome social obligation. However, Jack refuses to tell Algernon the location of his country estate.
Gwendolen and her formidable mother, Lady Bracknell, now call on Algernon, who distracts Lady Bracknell in another room while Jack proposes to Gwendolen. She accepts but seems to love him in large part because of his name, 'Ernest.' Jack accordingly resolves to himself to be rechristened "Ernest." Discovering them in this intimate exchange, Lady Bracknell interviews Jack as a prospective suitor. Horrified to learn that he was adopted after being discovered as a baby, in a handbag at Victoria Station, she refuses him and forbids further contact with her daughter. Gwendolen manages to covertly promise to him her undying love. As Jack gives her his address in the country, Algernon surreptitiously notes it on the cuff of his sleeve: Jack's revelation of his pretty and wealthy young ward has motivated his friend to meet her.
Act II: The Garden of the Manor House, Woolton
Cecily is studying with her governess, Miss Prism, in the (fictitious) village of Woolton, Hertfordshire. Algernon arrives, pretending to be Ernest Worthing, and soon charms Cecily. Long fascinated by uncle Jack's hitherto absent black sheep brother, she is predisposed to fall for Algernon in his role of 'Ernest' (a name she is apparently particularly fond of). Therefore, Algernon, too, plans for the rector, Dr. Chasuble, to rechristen him "Ernest." Jack has decided to abandon his double life. He arrives in full mourning and announces his brother's death in Paris with a severe chill, a story undermined by Algernon's presence in the guise of Ernest. Gwendolen now enters, having run away from home. During the temporary absence of the two men, she meets Cecily, each woman indignantly declaring that she is the one engaged to 'Ernest.' When Jack and Algernon reappear, their deceptions are exposed.
Act III: Morning-Room at the Manor House, Woolton
Arriving in pursuit of her daughter, Lady Bracknell is astonished to be told that Algernon and Cecily are engaged. The revelation of Cecily's wealth soon dispels Lady Bracknell's initial doubts over the young lady's suitability, but any engagement is forbidden by her guardian Jack: He will consent only if Lady Bracknell agrees to his own union with Gwendolen – something she declines to do.
The impasse is broken by the return of Miss Prism, whom Lady Bracknell recognises as the person who, 28 years earlier as a family nursemaid, had taken a baby boy for a walk in a perambulator and never returned. Challenged, Miss Prism explains that she had absent-mindedly put the manuscript of a novel she was writing in the perambulator, and the baby in a handbag, which she had left at Victoria Station. Jack produces the same handbag, showing that he is the lost baby, the eldest son of Lady Bracknell's late sister, and thus Algernon's elder brother. Having acquired such respectable relations, he is acceptable as Gwendolen's suitor.
Gwendolen, however, insists she can love only a man named Ernest. Lady Bracknell informs Jack that, as the firstborn, he would have been named after his father, General Moncrieff. Jack examines the army lists and discovers that his father's name – and hence his own original christening name – was, in fact, 'Ernest'. Pretence was reality all along. As the happy couples embrace – Jack and Gwendolen, Algernon and Cecily, and even Dr. Chasuble and Miss Prism – Lady Bracknell complains to her newfound relative: "My nephew, you seem to be displaying signs of triviality." He replies, "On the contrary, Aunt Augusta: I've now realised for the first time in my life the vital importance of being Earnest."
