Seventeen-year-old Catherine Morland is one of ten children of a country clergyman. Although a tomboy in her childhood, by the age of 17 she is "in training for a heroine" and is excessively fond of reading Gothic novels, among which Ann Radcliffe's Mysteries of Udolpho is a favourite.

Catherine is invited by the Allens, her wealthier neighbours in Fullerton, to accompany them to visit the town of Bath and partake in the winter season of balls, theatre and other social delights. She is soon introduced to a clever young gentleman, Henry Tilney, with whom she dances and converses. Through Mrs. Allen's old schoolfriend Mrs. Thorpe, she meets her daughter Isabella, a vivacious and flirtatious young woman, and the two quickly become friends. Mrs. Thorpe's son John is also a friend of Catherine's older brother, James, at Oxford where they are both students.

The Thorpes are not happy about Catherine's friendship with the Tilneys, as they correctly perceive Henry as a rival for Catherine's affections, though Catherine is not at all interested in the crude John Thorpe. Catherine tries to maintain her friendships with both the Thorpes and the Tilneys, though John Thorpe continuously tries to sabotage her relationship with the Tilneys. This leads to several misunderstandings, which put Catherine in the awkward position of having to explain herself to the Tilneys.