The musical opens in London’s Covent Garden as the wealthy late-night post-opera crowd crosses paths with the poor street vendors who are setting out to work. Mrs. Eynsford-Hill and her son, Freddy Eynsford-Hill, enter, both lavishly dressed. In the increasing commotion of the street and his mother’s demand for a taxi, Freddy collides with Eliza Doolittle, a young Cockney woman, who lets out a loud cry when her basket of flowers to sell is dumped on the street. Freddy tries to apologize, but Mrs. Eynsford-Hill insists that he hail a taxi immediately. Eliza confronts her, accusing her of raising him poorly if he can destroy a woman’s income for the entire day and not even reimburse her.

Colonel Pickering enters, also seeking a taxi. Eliza tries to sell him a flower. Pickering gives her his few cents in pocket change instead. Then someone in the crowd alerts Eliza that there’s a man who is writing down everything she says, presuming that he’s a police detective. Upset, Eliza raises a big uproar, begging Pickering in her brash Cockney accent not to let the man arrest her.