The Count O’Dowda, a hater of what he perceives as the modern vulgarity of England, hires a professional producer and actors to put on a play in his country estate, and then invites professional critics to attend. But unknown to him, his daughter Fanny, a student at Cambridge and a member of the Fabian Society, has written the play with the intent of morally shocking her father, and she hopes that the presence of professional critics will convince him of its artistic merit.

Within this framing, the play within the play concerns the Gilbey and Knox families. Both are highly respectable, and both of their children have secretly spent a fortnight in jail for assaulting a police officer. The families, along with a noble footman, a disreputable woman, and a French naval lieutenant, must navigate what it means to be respectable in the eyes of society, and what truly noble behavior entails.

Fanny’s First Play is a satire not only of society and morals, but of the theater of the day and of specific criticisms George Bernard Shaw’s works had drawn. The characters of the theater critics are based on actual critics of the day, and Shaw’s other works are discussed dismissively by them. It was originally performed with its authorship kept secret, but attendees and critics soon recognized it as Shaw’s work. The mystery around its authorship was good publicity, and it became Shaw’s longest running and most popular work.