Act 4. At Acres' lodgings, David tries to dissuade Acres from fighting a duel, but Acres is insistent that he fight. "David, no gentleman will ever risk the loss of his honour!" he says, but David insists that because Acres risks death, it is not worth it, saying, "Under favour, the surest way of not disgracing them, is to keep as long as you can out of their company."
A servant enters and announces the arrival of Jack Absolute. Jack comes in and asks Acres why he called him there, and Acres hands him the challenge for Ensign Beverley. Jack agrees to deliver the challenge, when suddenly the servant comes back in and announces the arrival of Anthony Absolute, looking for Jack. Before Jack leaves, Acres asks him to tell Beverley that he is "a determined dog."
Scene 2. At Malaprop's lodgings, Malaprop and Lydia discuss Jack Absolute and Beverley. Malaprop thinks Jack is very handsome indeed, but Lydia stubbornly insists that she still loves Beverley. A servant announces the arrival of Anthony and Jack Absolute, and Malaprop tells him to bring them up, before telling Lydia to "show [her] good breeding."
Lydia is determined to be impolite to Jack, so much so that she decides to not even look at him when he comes in, looking away from the door. Anthony and Jack enter and Jack notices that Lydia is refusing to look at him. He asks his father to leave them alone, but he will not, entreating his son to speak to Lydia. Finally, Jack resolves to alter his voice and speaks to Lydia in a "low hoarse tone."
With no other hope, Jack speaks to Lydia in an aside in his own voice, telling her to "suppress all surprise at present." When Lydia turns around and sees him, she recognizes him as Beverley, which confuses Malaprop and Anthony. Jack admits that, indeed, he has disguised himself as Beverley to win Lydia's affection, and Lydia disappointedly says, "So!—there will be no elopement after all!"
Anthony is mad that Jack would mount such an elaborate charade and compromise his reputation. Malaprop is also offended by Jack's ruse, realizing that it was he who wrote such unflattering descriptions of her in his letters. Anthony encourages Malaprop to forgive them and delight in the fact that they are in love, and the two elders leave the room, singing.
Jack goes to Lydia and notices that she is disappointed that he is actually a wealthy young captain. She says to him, "Then, sir, let me tell you, the interest you had there was acquired by a mean, unmanly imposition, and deserves the punishment of fraud.—What, you have been treating me like a child!—humouring my romance! and laughing, I suppose, at your success!" She bemoans the fact that she thought she was rebelling against her family, but was actually falling in love with precisely the person her aunt and father want her to marry.
As Jack flatters Lydia and looks at a picture of her, she bursts into tears, and storms out of the room, vowing not to marry him.
Scene 3. The North Parade. Lucius comes in and waits for Beverley, his opponent in the duel. Then, Jack enters, crestfallen at the fact that Lydia has denied him. "I could cut own throat, or any other person's, with the greatest pleasure in the world!" he says. He runs into Lucius, who wants to fight him, even though Absolute does not understand why. They agree to meet that night at 6, the same time Lucius is to fight Beverley.
When Lucius leaves, Faulkland enters and asks Jack what is wrong. Jack tells him that Lydia does not love him and that Lucius has challenged him to a duel. He asks Faulkland to be his second at the duel, but Faulkland tells him he is very troubled by the fight he got into with Julia, and cannot attend the duel. A servant comes in and hands Faulkland a letter from Julia.
Faulkland is too scared to read the letter, so Jack opens it and reads it. The letter says that Julia wishes to speak with him and is signed "Yours ever and truly," but Faulkland is still not convinced of her love. Faulkland says to Jack, "...don't you think there is something forward, something indelicate, in this haste to forgive?" Jack reproaches him and leaves.
Left alone, Faulkland devises a plot to use the duel as a way of testing Julia's love for him.
Act 5. In Julia's dressing room, she reads a letter from Faulkland about a "dreadful accident." Faulkland enters and tells Julia that he was drawn into a quarrel and must flee the country. Julia tells him, "My heart has long known no other guardian—I now entrust my person to your honour—we will fly together." Faulkland comes up with a number of reasons why she shouldn't come, but Julia proves steadfast in her devotion to him.
Satisfied with her loving words, Faulkland reveals that he completely fabricated his need to leave the country. While Julia is relieved, she is also angered by his doubtfulness. She tells him that she has devoted herself to him in the same way she devoted herself to her father who passed away soon after she and Faulkland became acquainted. She then tells him that his deception is insulting and cruel and that she will never be his. She exits, leaving Faulkland heartbroken. After a brief monologue, he exits.
Lydia and a maid come in, looking for Julia. When Julia comes back in, Lydia notices that she has been crying, but Julia refuses to say why. Lydia then tells Julia about her misfortune, the fact that she has been duped by Jack, but Julia tells her that she already knew, because Faulkland told her. Lydia vows never to marry Jack, but Julia insists that Jack loves her sincerely, and that she ought to forgive him.
Suddenly, they are interrupted by Malaprop, Fag, and David. Malaprop tells the servants to tell Julia and Lydia about the duel that is to take place between Jack, Faulkland, Acres and Lucius. Malaprop is distressed to hear that Lucius is involved, and all three of the women decide that they must go to the dueling location and stop it.
Scene 2. Jack enters with a sword, waiting for Faulkland. Suddenly, Anthony appears, and asks Jack where he is going. Jack lies and says he is going to Lydia to beg for forgiveness, but Anthony notices his sword and becomes alarmed. Jack again lies and tells his father that he is bringing the sword to Lydia as a dramatic suicide prop to whet her appetite for drama and romance. Anthony believes him and lets Jack go.
As Jack exits, David enters and asks Anthony why he didn't stop his son, revealing that Jack is on his way to a duel. Anthony asks David to take him to the dueling place.
Scene 3. At King's-Mead-Fields, Lucius and Acres enter with pistols. They argue about how far away the dueling parties should be from one another. They are interrupted by the arrival of Faulkland and Jack. Jack reveals that he was pretending to be Beverley all along, and Acres does not want to fight, as Faulkland and Jack are his friends.
Lucius is undeterred, however, and wants to fight, but just as he draws his sword, Anthony, David, Malaprop, Lydia, and Julia all enter. Anthony asks Lucius why he challenged Jack to a duel. "Your son, sir, insulted me in a manner which my honour could not brook," Lucius says, before looking at Lydia and calling her "Delia," the name he uses in his letters.
Confused, Lydia tells Lucius that she has come to offer Jack her hand in marriage, and Jack is overjoyed. Jack then addresses Lucius, telling him that there must be some misunderstanding. Acres says that he will give up his pursuit of Lydia, and Lucius pulls out the letters he believes are from Lydia. Lydia looks at the letters, and tells him they are not from her, before exiting with Jack.
Malaprop reveals to Lucius that she is Delia, and Anthony suggests that Lucius should marry Malaprop, but he refuses. Everyone leaves the stage except Julia and Faulkland. Julia forgives Faulkland for lying to her and they reconcile. Anthony encourages their union and the other characters come forward. Julia speaks the final line of the play, saying, "...while Hope pictures to us a flattering scene of future bliss, let us deny its pencil those colours which are too bright to be lasting.—When hearts deserving happiness would unite their fortunes, Virtue would crown them with an unfading garland of modest hurtless flowers; but ill-judging Passion will force the gaudier rose into the wreath, whose thorn offends them when its leaves are dropped!"
An epilogue by the author addresses the audience. Originally uttered by Mrs. Bulkley, adopting the identity of the Muse, it reads, "One moral's plain," cried I, "without more fuss;/Man's social happiness all rests on us:/Through all the drama—whether damn'd or not—/Love gilds the scene, and women guide the plot./From every rank obedience is our due/D'ye doubt?—The world's great stage shall prove it true." She says that women carry the torch of love, and that love is central to all matters.
At every moment in which Jack's plot could potentially be revealed, something gets in the way to prevent the truth from coming to the surface. These convenient elisions always have a comical effect, for indeed they occur right in the nick of time, saving Jack from getting discovered. For instance, in Act 4, Scene 2, Anthony Absolute and Jack come to visit Lydia and Malaprop, but Lydia feels so averse to meeting him that she hides her face and refuses to look at him. If she looked at him, she would realize that he and Ensign Beverley are one and the same, but instead she prevents herself from learning her beloved's true identity for a time.
This does not last long, however, as Anthony and Malaprop force a meeting between Jack and Lydia. As soon as Lydia turns around, she recognizes her beloved as Ensign Beverley, and Jack must come out with his plot to everyone. Malaprop and Anthony are both enraged by the deception for a moment, but soon enough, they decide to look past it and take heart in the fact that the two young lovers have found one another. With their approval, it is only Lydia who needs convincing from Jack that his love is worth the deception.
A great deal of comic mileage comes from the fact that Lydia's preferences in a man are the complete opposite of what one would expect of a noblewoman. Instead of wanting a monied captain, she wants a lowly ensign with whom to live in poverty. When Jack's identity comes out, however, it becomes clear that her desires for a poor mate were less about poverty itself than about rebelling against her station. Incensed, she tells Jack, "So, while I fondly imagined we were deceiving my relations, and flattered myself that I should outwit and incense them all—behold my hopes are to be crushed at once, by my aunt's consent and approbation—and I am myself the only dupe at last!" Her desire to marry an ensign and to forfeit her inheritance was wrapped up in her desire to disobey her protective guardians, to make a decision for herself for once.
While both Jack and Faulkland's deceptions are meant to ensure the love of their respective mistresses, their backhandedness proves to have the opposite effect, at least at first. Offended to have been duped by Jack, Lydia refuses his hand at first. Similarly, Julia is heartbroken when she realizes that Faulkland has only pretended to need to leave the country in a bid to test her affections. In the final act of the play, the unions between the two couples are broken, and it seems as though everyone will end up uncoupled, and perhaps, killed in a duel.
In the end, the play is a romantic comedy, a lighthearted confection about the foolishnesses and beauty of romantic love. So it's no surprise that the two central couples, Jack and Lydia and Julia and Faulkland, are finally reunited and hope to live happy lives with one another. The epilogue only further amplifies the theme of romantic love, a series of rhyming couplets about the fact that while it may seem as though men have the upper hand in society, it is women who hold the keys to his social happiness and control the tides of romance.