Titus - a son and heir for the 76th Earl of Groan - is born. In the castle's kitchens, a new kitchen boy, Steerpike, rebels against the cook, Swelter, and runs away. He invades the bedroom of Lord Groan's daughter, Lady Fuchsia, who finds herself strangely attracted to him and takes him on a visit to the family's physician, Dr Prunesquallor.

Steerpike accepts a place as Prunesquallor's assistant, meaning a dramatic rise in his status, and is taken into the confidence of the Earl's twin sisters, Lady Cora and Lady Clarice. Working on the sisters' feelings of injustice, he persuades them to set fire to the castle library, dear to their brother's heart. Steerpike knows - but the sisters do not - that the rest of the family is in the library at the time, with the doors barred.