Decline and Fall sees Paul Pennyfeather as an inoffensive divinity student at Oxford University in the 1920s, who is wrongly dismissed for indecent exposure having been made the victim of a prank by The Bollinger Club.
Dr Fagan is the headmaster of Llanabba, an obscure public school in Wales where Paul first finds employment and works with fellow teacher Grimes. It is at the school that he meets the Honourable Mrs Margot Beste-Chetwynde, who is the mother of one of the pupils.
When Paul Pennyfeather is unfairly expelled from Oxford University, he finds his only option is to go and teach at a substandard boarding school in rural Wales. There he meets a colourful cast of characters, including the alluring Margot Beste-Chetwynde, a wealthy widow with designs on the naeve Paul.
Paul Pennyfeather finds himself tutoring the son of Margot Beste-Chetwynde over the school summer holidays. As he tries to act natural among the higher echelons of 1920s society crowding Margot's elegant home, Paul wonders whether the feelings he fosters for the wealthy and alluring widow are returned.
Valiantly taking the fall for the murky deeds of his fiancee Margot, Paul Pennyfeather finds himself in deep trouble with the law. Will Paul be able to escape imprisonment, and will Margot wait for him if he doesn't?