Scene 1: Outside Covent Garden
As people leaving the opera look for taxis, Freddy Eynsford Hill accidentally knocks over Eliza's basket of flowers. Her lamentations are taken down by a bystander, at first suspected of being a policeman, but soon revealed to be Henry Higgins, an expert on phonetics, who astounds everyone by his ability to identify their life stories from their speech, including Colonel Pickering, an expert on Indian dialects, who has come to London to meet Higgins.
Higgins complains that most Englishmen are incapable of speaking their own language properly (Why Can't the English) - Eliza's accent will keep her in the gutter; but in six months he could teach her to speak so well that she would pass muster at an embassy ball. He invites Pickering to stay with him, throwing Eliza a pocketful of money, arousing the envy of her friends (Wouldn't it be Loverley).
Scene 2: Tenement section, Tottenham Court Road
Doolittle learns of Eliza's good fortune but fails to get any money out of her, despite his view that it is the duty of children to support their parents (With a little bit of Luck).
Scene 3: Higgins' study
Higgins is demonstrating his methods to Pickering, when Mrs Pearce, his housekeeper, announces a young woman with a dreadful accent. His initial interest is dispelled when he finds it is Eliza, whose speech he already has a record of, but she, having overheard his remarks about improving her accent, insists she wants lessons. Intrigued, he accepts Pickering's proposal of a bet that he can pass her off as a duchess at the end of six months. Although she is suspicious of his dictatorial attitude, Eliza is mollified by Pickering's more courteous attitude and decides to stay; she is taken off by Mrs Pearce to be bathed. In answer to Pickering's queries as to his character where women are concerned, Higgins assures him that he has no place for them in his life (I'm an ordinary man).
Scene 4: The tenement section, Tottenham Court Road
Doolittle learns that Eliza has apparently "moved in with a swell," and resolves to take advantage of the situtation.
Scene 5: Higgins' study
Doolittle arrives to claim his daughter, but it is immediately apparent to Higgins that he is only after money. Doolittle admits this freely. He settles for £5. On the way out he bumps into Eliza, washed and dressed in clean clothes, and at first does not recognise her. Eliza starts her lessons, but does not take kindly to Higgins' autocratic methods (Just you Wait). A servants' chorus comments as the lessons continue, culminating in Eliza's mastery of a difficult vowel sound and the correct placement of the letter "h" (The Rain in Spain). The delighted Higgins whirls her into a dance and decides the time has come to test her in public. She is exhilarated (I could have danced all Night).
Scene 6: Outside Ascot
Higgins and Pickering take Eliza to Mrs Higgins' box at Ascot, explaining her background and their wish to test her new accent in polite society.
Scene 7: Ascot
Eliza startles the company with her "small talk" - slum anecdotes in an impeccable accent, and, given a horse to back by Freddy (who is greatly taken by her), calls on it to move its "bloomin' arse."
Scene 8: Outside Higgins' house
The infatuated Freddy keeps watch (On the Street where you Live), despite Mrs Pearce's message that Eliza wishes to see no one.
Scene 9: Higgins' study
Pickering is nervous but Higgins is quietly confident as they prepare to take Eliza to a ball. When she enters Pickering is full of admiration, and Higgins concedes that she doesn't look bad.
Scene 10: The promenade ouside the ballroom at the embassy
Eliza has passed the first hurdle, being accepted by her hostess, but Zoltan Karpathy, claiming to have been taught by Higgins and now to be indispensable to the royalty of Europe for his linguistic skills, is curious about her, and evading Higgins, dances off with her.
Scene 1: Higgins' study
It is 3 a.m. Pickering congratulates Higgins on his successful experiment, while Higgins gloats at Karpathy's claim to have unmasked Eliza as a fraud and his declaration that she is a Hungarian princess, (You did it). Eliza sits in stony silence until Higgins asks: "What the devil have I done with my slippers?" She throws them at him. She is distresssed because neither he nor Pickering has acknowledged her part in the triumph. She decides to leave.
Scene 2: Outside Higgins' house
Freddy, still soliquizing in the street, is delighted when Eliza appears, but she demands action rather than more words from him (Show me).
Scene 3: Covent Garden flower market
Eliza visits her old haunts, unrecognised in her new finery and accent. Her father is about to be married, having become a victim of middle class respectability as the result of being left money by an American philanthropist, who had been told by Higgins, as a joke, that the most original moralist in England was a dustman called Alfred Doolittle (Get me to the Church on Time).
Scene 4: The upstairs hall, Higgins' house
Higgins and Pickering institute a search for Eliza, the former claiming to find her departure completely illogical, not the sort of thing a man would have done (Hymn to him).
Scene 5: The garden of Mrs Higgins' house
Mrs Higgins sympathises with Eliza. Higgins arrives and tells her that if she comes back he will treat her just as he always has. She says she will marry Freddy and earn her living by teaching the science of speech he has taught her, having realised that she does not need him (Without you).
Although trying to pretend otherwise, Higgins regrets Eliza's absence (I've grown accustomed to her Face).
Higgins is playing over his early recordings of Eliza's speech when she returns. Unable to express his joy openly, he says: "Eliza? Where the devil are my slippers?" She smiles.