Two servants, Fag and Thomas , run into one another on the streets of Bath. Thomas explains that his master Sir Anthony Absolute decided on the spur of the moment to bring his entire household to town. Fag teasingly tells Thomas that he no longer works for the younger Absolute ; his new master is Ensign Beverley . He explains that Absolute has taken on the identity of an ensign to woo the beautiful, young heiress Lydia Languish .
In Lydia’s dressing room, Lydia and Lucy discuss the novels that Lucy has procured for her mistress. They are surprised by the entrance of Lydia’s cousin Julia , who has just arrived in Bath with her guardian Sir Anthony. Lydia hastens catches her cousin up on her news: she was barred from communicating with her lover, Beverley,when her guardian Mrs. Malaprop discovered their affair. Mrs. Malaprop thinks an ensign is an unsuitable match for her niece. Meanwhile, Mrs. Malaprop is secretly corresponding with an Irish baronet name Sir Lucius .
Julia can’t believe that Lydia really intends to marry a poor ensign, but Lydia is determined to do so and give up two-thirds of her fortune as a result. Julia thinks this silly, but Lydia mocks Julia’s own fiancé Faulkland’s silly jealousy. Julia defends Faulkland’s bad temper as the result of his love for her and insecurity about deserving her.
Later, Sir Anthony arrives to visit Mrs. Malaprop, and together they chide Lydia for her interest in Beverley. Sir Anthony blames such disobedience in a girl on reading. Heargues that girls should be illiterate, while Mrs. Malaprop makes a garbled case for the areas of study appropriate for young ladies, attempting to use sophisticated language and instead sounding ridiculous. Sir Anthony has proposed marrying Lydia and Absolute, and they discuss how to convince the young people to accept the match.
After Sir Anthony leaves, Mrs. Malaprop reflects on her own love affair with Sir Lucius, and worries about how Lydia found out about it. She asks Lucy if she told Lydia, which Lucydenies. Mrs. Malaprop then gives Lucy another letter for Sir Lucius.Once she’s alone, Lucy reflects on how much profit she’s made in tips and gifts delivering letters for all these lovers, and how, while pretending to be simple, she actually revealed Lydia and Beverley’s love affair to Mrs. Malaprop, and led Sir Lucius to believe that he’s corresponding with Lydia instead of with her aged aunt.
In Absolute’s lodging, Fag and Absolute plan how to keep Sir Anthony from learning about Absolute’s courtship of Lydia (in his disguise as Beverley). Faulkland enters and urges Absolute to ask Mrs. Malaprop and his father for Lydia’s hand in marriage, but Absolute isn’t sure that Lydia will have him once she realizes he’s rich and marrying him isn’t an act of rebellion. Faulkland, meanwhile, has been in a terrible mood; he says it’s because he worries about Julia when they’re separated. Absolute reveals that Julia is well and in Bath, then convinces him to stay to hear an update on her from Acres , a neighbor of the Absolutes in the countryside. Acres comes in and tells them that Julia has been in perfect health and charms everyone she meets. Faulkland storms out in a jealous fit.
Acres, who knows nothing about Absolute’s courtship of Lydia, now describes to Absolutehis own ridiculous attempts to become more fashionable as he tries to court Lydia. A bit later, Sir Anthony arrives and tells Absolute that he wants to make his son’s fortune by marryinghim to someone.But Sir Anthonyrefuses to reveal who the woman is, saying that Absolute owes him unconditional obedience. Absolute responds that he’s already in love and cannot obey his father, who curses him and storms off.
Meanwhile, Lucy delivers a letter from “Delia” to Sir Lucius. Sir Lucius still believes that “Delia” is Lydia. Fag has observed all this, and after Sir Lucius leaves he threatens to tell Ensign Beverley that Lucy is also acting on behalf of Sir Lucius, but Lucy explains that the letters actually come from Mrs. Malaprop. She then tells Fag that his master has an even more formidable new rival: Absolute. Fag gleefully hurries off to tell Absolute the news that the woman he loves and the woman his father intends him to marry are one and the same.
Not long after, Absolute spots his father on the North Parade and makes up with him. Without disclosing that he’s already courting Lydia as Ensign Beverley, Absolute promises to marry any woman his father commands him to marry, no matter how old or ugly she is. Sir Anthony is disgusted that Absolute seems not to care whether his future wife will be beautiful.
Julia enters her lodgings to find Faulkland there. She asks Faulkland why he doesn’t seem excited to see her, to which he says that he’d heard she had been jolly without him and so pretended indifference to her. She says she only put on a happy face so that her friends would not blame him for making her unhappy. He is momentarily reassured, but then presses her again, doubting that she truly loves him and does not merely feel duty-bound to marry him. She runs off sobbing.
Captain Absolute goes to visit Mrs. Malaprop at her lodgings. She is very impressed with his appearance and gallantry, and he flatters her. She pulls out a letter from Beverley (actually from Absolute) and they read it together. In the letter, Beverley mocks Mrs. Malaprop’s pretention and ridiculous misuse of language and promises to find a way to see Lydia with Mrs. Malaprop serving as an intermediary. Absolute scoffs with Mrs. Malaprop at this impudence, then asks if he may meet Lydia. Mrs. Malaprop calls Lydia down, and departs. Lydia is shocked to see her lover, Beverley. He tells her that he posed as Absolute so as to be allowed to see her, and she is delighted that he tricked her aunt. Mrs. Malaprop eavesdrops, but misinterprets what the two lovers are saying, and thinks that Lydia is rejecting Absolute cruelly. She intervenes and sends Lydia out of the room.
Sir Lucius arrives at Sir Acres lodgings and Acres explains that he has come to Bath to pursue Lydia, who is now being courted by a man named Beverley. Although there are no grounds for it, Sir Lucius convinces Acres that he should challenge Beverley to a duel. Acres is very nervous at the prospect, but allows Sir Lucius to guide him and write the letter of challenge. Sir Lucius says he may also soon issue a challenge to a captain who insulted Ireland. A while later, David tries to convince his master not to send the letter of challenge to Beverley. David’s worries about the duel frighten Acres, but he is determined to push forward with it. Absolute then arrives, and Acres asks him to deliver the letter to Beverley, since he knows Absolute and Beverley are acquainted.
Mrs. Malaprop is praising Absolute to Lydia, who, believing that Mrs. Malaprop has only actually met Beverley, insists that Beverley is also charming. Sir Anthony and Captain Absolute arrive, but Lydia will not look at Absolute. She wonders, however, why her aunt does not recognize that this is a different man from the one she met earlier. Sir Anthony urges Absolute to speak, but he claims that he is too overcome with nervousness to do so. Finally, he realizes his secret is bound to be discovered. He urges Lydia not to be surprised, but she exclaims “Beverley,” upon hearing his voice. At first Mrs. Malaprop and Sir Anthony think Lydia has gone mad, but then they realize that Absolute has deceived them all. Sir Anthonyis pleased that Absolute was lying when he pretended utter indifference to his wife’s beauty. Mrs. Malaprop is appalled that Absolute wrote that letter mocking her, but at Sir Anthony’s urging they leave the couple alone together. Lydia, however, is furious that Absolute deceived her. She throws away a miniature portrait of him that she had carried and says that she will not marry him. Sir Absolute and Mrs. Malaprop reenter and are dismayed to see an angry scene instead of a loving one.
Absolute walks on the North Parade, muttering about his ruined hopes. Sir Lucius spots him and, giving no explanation, challenges him to a duel. Absolute tries to ascertain Sir Lucius’s reasons, but cannot. Yet he agrees to duel Sir Lucius that night. Sir Lucius departs, and Absolute runs into Faulkland. Absolute tells him that he has been rejected by Lydia and challenged by Sir Lucius, and asks Faulkland to be his second in the duel. Faulkland agrees. A servant arrives with a letter from Julia for Faulkland, in which she pardons him for his bad behavior. Although he had been wracked with guilt for having behaved badly towards her, he now thinks it is improper of her to give forgiveness without first being asked. Absolute tells him that he cannot listen to any more of the problems Faulkland invents for himself and exits. Faulkland, to himself, saysthat the duel has given him a new idea for a way to make sure that Julia truly loves him.
Faulkland tells Julia that he must flee England, suggesting that he killed someone in a duel. Julia says she will elope with him. He asks her to consider: they may have little money, and he may become more quarrelsome than ever. Still, she says she wants to be with him. Overjoyed at having proved the sincerity of her love, Faulkland reveals that he fabricated the story of the duel. Julia is furious; she says that this deception is the final straw, and that she will not marry him now. A while later, Lydia wanders in looking for Julia, who she expects to convince her to take Absolute back. She tells Julia about Absolute’s deception, and Julia confesses that Faulkland had already told her about it. Lydia is angry at this, but begins to reminisce about the romantic times she and Beverley shared. Julia says she is in no mood to treat her cousin’s behavior as humorous: she begs Lydia to be reasonable and not ruin a potentially happy marriage because of a caprice. Fag then enters with Mrs. Malapropand tells the ladies that Faulkland, Absolute, Sir Lucius and Acres are all to be involved in a duel.They all rush off to try to stop it.
As Absolute awaits the duel, Sir Anthony sees him. Absolute successfully hides the fact that he’s going to fight a duel, but moments after he departs David runs up and tells Sir Anthony what’s going on. They too hurry of to try to stop it.
On King’s-Mead-Fields, a little out of town,Acres and Sir Lucius await their dueling opponents. Sir Lucius mentions the possibility that Acres will be killed, and Acres begins to lose courage. Faulkland and Absolute approach. Sir Lucius assumes that Faulkland is Beverley, but Acres recognizes that neither man is Beverley. Sir Lucius then encourages Acres to fight Faulkland in Beverley’s stead, but Acres refuses. Absolute confesses that Beverley was a false identity he had taken on, and says that he is willing to fight Acres in Beverley’s stead. Acres still refuses to fight. Sir Lucius calls Acres a coward, and Acres accepts the insult without challenging him. Sir Lucius and Absolute begin to fight, and at that moment the other characters hurry in Sir Anthony demands an explanation for how Absolute came to fight, but gets none. Mrs. Malaprop says that Lydia is terrified, and urges Lydia to tell Absolute that she still loves him. Sir Lucius cuts in and says that he can explain Lydia’s silence, but Lydia then speaks up, saying that she loves Absolute. Sir Lucius then produces a love letter from Delia and demands whether Lydia wrote it. Lydia denies writing it, and Mrs. Malaprop confesses that she is Delia. Sir Lucius is not interested in marrying Mrs. Malaprop. and he says he foregoes his claim to Lydia. Sir Anthony advises Julia to marry Faulkland, promising that his jealous temperament will improve after they are married, and Acres promisesto throw a party for the newly engaged couples.