A Professor of Phonetics, Henry Higgins, is listening to various speech patterns outside St Paul's Cathedral in Covent Garden, London. He bumps into his old colleague, Colonel Pickering, who has long admired the work that Higgins has achieved in the world of phonetics.
Overhearing the strong cockney accent of a flower girl, Eliza Doolittle, Colonel Pickering wager Higgins that he cannot turn Eliza from a cockney flower girl into a lady who will be accepted by the upper classes as one of their own. Intrigued by the challenge and confident of his own ability, Higgins installs Eliza into his home and proceeds to coach her and try to turn her into the lady that Pickering has challeged.
Meanwhile, coal-man Alfred Doolittle, Eliza's father, always one with an eye to the main chance, learns of the situation and attempts to capitalise on the events unfolding - but he is unsuccessful.
More succesful, however, is Higgins. Eliza is learning how to speak and act as an upper class lady and she is taken to the social event of the season, the race meeting at Ascot, where she manages to charm everyone - in spite of the odd lapse in speech!!
Later she attends a magnificent ball where she is studied most intently by one of Higgins's ex students, Zoltan Karpathy who suggests to all around that Eliza is obviously a member of a European noble family. Once again Eliza has carried off the deception, but receives no praise or acknowledgement from Higgins. Deeply upset by his lack of feeling she leaves his home to stay with his mother, Mrs Higgins.
Higgins cannot understand Eliza's actions and visits his mother's home where he is told by Eliza, in no uncertain terms, that he is a rude, selfish, egomaniac. He leaves, and back in his study muses over the differences between a woman and a man.
The door opens and Eliza is back. Irascible as ever, Higgins demands his slippers - and the curtain falls.
