Northanger Abbey is the coming-of-age story of a young woman named Catherine Morland. It is divided into two sections, Book I and Book II. The two Books differ significantly from each other in setting and, to a degree, in tone. Book I begins when the Allens, family friends of the Morlands, offer to take Catherine with them to Bath, a resort for the wealthier members of British society. The 17-year-old Catherine eagerly accepts the Allens' invitation. Catherine is young and naive. Her life has been relatively sheltered, so Bath is a new world for her. Book II begins with the arrival of Henry's older brother, Captain Frederick Tilney. Isabella quickly catches the eye of the captain and, dismayed by the discovery of James's modest income, begins to flirt with Frederick. Eleanor invites Catherine to visit the Tilney home in Northanger Abbey. The invitation is seconded by Eleanor's father, General Tilney. Catherine eagerly accepts the invitation, delighted at the prospect of visiting a real abbey and at seeing more of Henry."