Gwendolen and Cecily are seeking sanctuary in the morning room at the Manor House. They peer out the window in curiosity at the two men.
The girls notice that the men haven’t followed them into the house and are eating muffins. They’re worried that the guys don’t seem to be noticing them at all.
A moment later, when the two guys start walking toward the house, the women are affronted and agree to give them the silent treatment.
But that soon falls apart. Cecily breaks her silence to ask Algernon why he pretended to be Jack’s brother. He answers candidly—to "have an opportunity of meeting you" (III.15). Cecily melts.
Then it’s Gwendolen’s turn. She asks Jack why he pretended to have a brother. Before he can answer, she suggests that it was possibly so that he could have an excuse to come up to town to see her as often as possible. He confirms it.
Satisfied, the girls forgive the men. But there’s a still a problem. The girls confront the guys in loud unison: "Your Christian names are still an insuperable barrier. That is all!" (III.29).
In other words, the girls can’t possibly marry them if their names aren’t Ernest.
In response, the men answer in unison: "Our Christian names! Is that all? But we are going to be christened this afternoon" (III.30).
Seeing that their beloveds are brave enough to endure such a harrowing ordeal as a christening for their sake, the women rush into their lovers’ arms.
Merriman enters, sees all the hugging going on, and coughs loudly. He announces the arrival of Lady Bracknell. The startled couples separate.
Lady Bracknell loses no time in asking Gwendolen just what she’s doing. At the news that she’s engaged to Jack, Lady Bracknell turns her wrath on him. She orders that all communication between them must stop immediately and ignores his protests.
Then she turns to Algernon and asks if this is where Bunbury resides. Caught by surprise, Algernon answers no, then stutters that Bunbury is actually dead. He died by exploding. Lady Bracknell is appalled by his method of death, considering it a "revolutionary outrage" (III.54), but is glad that the matter is settled.
Onto business. Lady Bracknell asks Jack who is that young person holding Algernon’s hand so inappropriately.
When she learns Algernon is engaged to Cecily, she comments that there must be something in the air here that is particularly exciting. Because the number of engagements here "seems to me considerably above the proper average that statistics have laid down for our guidance" (III.61).
Slyly, she asks if Miss Cardew has any relations to the railway stations in London.
Jack is fuming, but coldly answers no and recites Cecily’s proper parents, plus their address. He assures her that she can find the same information in the Court Guides. And he lists off all the documentation he has of Cecily—including birth certificates, baptism records, incidents of illness, and vaccinations.
Lady Bracknell brushes him off, telling Gwendolen it’s time to leave.
As they exit, she asks offhand if Miss Cardew has any amount of fortune.
Oh, Jack answers, just a hundred and thirty thousand pounds.
Lady Bracknell freezes. Suddenly, Cecily looks much more attractive to her. With Cecily’s eager cooperation, Lady Bracknell inspects her profile and declares she has "distinct social possibilities" (III.75). Finally, she gives her consent. She even allows Cecily to call her Aunt Augusta.
But Jack has other ideas. As Cecily’s legal guardian, he refuses to give consent for her to marry Algernon. When Lady Bracknell, insulted, asks what could possibly be wrong with Algernon, Jack reveals that Algernon has lied—deceiving his whole family into thinking he was the nonexistent younger brother, Ernest.
On top of that, Jack continues, he not only drank an entire bottle of his best wine, but also ate every single muffin at tea. Jack stands by his verdict; he won’t give Algernon consent to marry Cecily.
Lady Bracknell, however, has hope. After learning Cecily is eighteen, Lady Bracknell says it won’t be long before she comes of age and she can make her own decisions.
But Jack interrupts, saying her grandfather’s will dictates she won’t come of age until she’s thirty-five.
Although Lady Bracknell doesn’t think the wait is that bad, Cecily is impatient and declares she can't wait that long.
Finally, Jack deigns to negotiate: if Lady Bracknell will give consent for him to marry Gwendolen, he’ll consent to let Algernon marry Cecily.
Lady Bracknell flatly refuses and tells Gwendolen to get ready to go. They’ve already missed five trains back to town.
Dr. Chasuble enters at this crucial moment to announce that everything is ready for the christenings. Lady Bracknell will not hear of such nonsense.
Jack sadly agrees to call off the christenings, because there’s no point now. Nobody is getting married.
This news saddens Dr. Chasuble, but he’s glad to have some free time this evening. He’s heard that Miss Prism has been waiting for him in the vestry.
Lady Bracknell starts at the name. Apparently they have a history.
Jack tries to explain that Miss Prism is Cecily’s esteemed governess. But this has no impact on Lady Bracknell. She orders Chasuble to send for Miss Prism at once.
At the sight of the stern Lady Bracknell, Miss Prism stops dead in her tracks, and turns around with the intention of running away.
Prism! Lady Bracknell spits. Miss Prism approaches humbly.
Lady Bracknell recites Prism’s crime: twenty-eight years ago, Miss Prism left Lord Bracknell’s house with a perambulator (read: a baby stroller) containing a male child.
Both of them disappeared without a trace. Weeks later, the police found the perambulator in Bayswater with an especially sappy three-volume novel inside. But the baby was gone.
Prism, Lady Bracknell screeches, where is that baby?
Shamed, Miss Prism confesses. She doesn’t know where the child is, but she tells what happened the best she can. On that fateful day, she not only had the baby in the perambulator with her, but the prized three-volume novel she had written, contained in an old hangbag.
Later that day, she got confused and accidentally put the book into the perambulator and the baby into the handbag.
Jack, who’s been listening intently, asks where she sent the handbag. Miss Prism confesses she deposited it at a cloakroom in Victoria Station (presumably to be sent to a potential publisher), the Brighton line.
At this news, Jack runs up to his room, leaving the others baffled. It sounds like things are being frantically thrown around.
After some time, Jack returns with a black leather handbag. He asks Miss Prism to inspect it and decide whether or not it’s the one she owned. After a few moments, Miss Prism declares that it is indeed hers. She points to the lock, which is engraved with her initials, as proof.
Jack smiles and reveals that he was the baby inside the handbag. Then he impulsively hugs Miss Prism, screaming in joy, "Mother!" (III.148).
But Miss Prism recoils, saying that she is not married. How could he dare insinuate such a thing? But Jack is in a generous mood and forgives her, only to hug her again.
Stunned, Miss Prism detaches herself and points to Lady Bracknell. That woman, she says, can tell you who you really are.
Lady Bracknell delivers the stunning news. "You are the son of my poor sister, Mrs. Moncrieff, and consequently Algernon’s elder brother" (III.153).
Jack is beside himself with joy, glad because this means that he had been telling the truth all these years; he does indeed have a younger brother. He grabs Algy and goes around the room, introducing each and every person to his "unfortunate brother," Algernon.
Gwendolen finally asks the question that’s been on our minds. What is Jack’s real name? He must remember that his marriage depends on it.
Jack turns to Lady Bracknell for the answer. She answers that he was indeed christened, and—as befits the eldest son—was named after his father. But, unfortunately, she cannot remember the General’s name.
Neither can Algy, because their father died when he was a baby.
But Jack has an idea. His father’s name would appear in the Army Lists, wouldn’t it?
Jack turns to the bookcase and tears out volumes until he finds the Army List he wants. He flips through the M's until he finds the Moncrieff entry. He reads out the Christian name: Ernest John.
He shuts the book and turns to Gwendolen with the suspenseful news that his name really is Ernest. He hasn’t been lying after all.
Lady Bracknell now remembers that the General’s name was Ernest. She knew she had a reason for disliking that name.
This clears the way for a love-fest. Gwendolen rushes into Jack’s arms. Dr. Chasuble (Frederick!) embraces Miss Prism (Laetitia!). Algernon sweeps Cecily off her feet.
There’s general chaotic joy.
When Lady Bracknell tries to put a damper on things by saying Jack is "displaying signs of triviality" (III.180), Jack replies suavely that, on the contrary, "I’ve now realised for the first time in my life the vital Importance of Being Earnest."