Algernon Moncrieff welcomes his friend Ernest Worthing in for a visit. Through an incident with a cigarette case and an unlucky inscription, Ernest is forced to confess that his name is really Jack. The story goes like this: in the country, Jack must lead the boring life of responsible guardian for his pretty, young ward Cecily. So he made up a seedy younger brother named Ernest, who is the urban socialite.
Cecily, we learn, is a bit too interested in Ernest for her own good. Whenever Jack feels like it, he visits London on the pretense that he’s cleaning up Ernest’s messes. After all, as the older brother he must be responsible for getting his younger brother out of trouble. Instead, Jack takes on the name Ernest and goes partying around town. Algernon is amused by this discovery and reveals that he has a similar nonexistent friend. Algernon's friend is a perpetual invalid named Bunbury, who allows Algernon to visit the country whenever he likes.