When Paul Pennyfeather is unfairly expelled from Oxford, he finds that his only option lies in teaching at a substandard Wales boarding school. There, he meets a colourful cast of characters, including the alluring Margot Beste-Chetwynde, a wealthy widow with designs on the naïve Paul.

Paul finds himself tutoring Peter, the young son of Margot Beste-Chetwynde over 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 Margot's murky deeds, Paul finds himself in deep trouble with the law. Will he be able to escape imprisonment, and will Margot wait for him if he doesn't?