The proof positive that parody can outlive the thing parodied -- there are books that our heroine and her friend discuss that were thought to be Austen's inventions for a long time. It sets the tone perfectly in the opening, where we are gravely introduced to Catherine, with the narrator exclaiming in surprise over every condition and attribute that does not match the life of a Gothic heroine, starting with her mother's inexplicable failure to die in childbirth.
But, although her neighborhood affords no opportunities for adventure, and indeed, no lord, no foundling, no ward of her father's, and no sons of the squire to be a suitable object of her love, obviously so dire a situation could not trap her. A local couple bring her along when they visit Bath, which leads to her meeting a young man named Tilney, and then a family, the Thorpes, whose son is a friend of her brother's at Oxford, and whose daughter Isabella soon becomes Catherine's fast friend. Plays, dances, walks, and carriage rides give them a stage for their interactions, leading to Isabella's engagement to Catherine's brother, and Catherine's invitation to visit the Tilneys' home, the title Northanger Abbey.
It combines a trip to visit a castle, a laundry list, discussion of a marriage settlement, a man who habitually rattles on, saying a lot of nonsense in total indifference to its truth, Catherine's being asked to have the first dance by a man, an attempt to break a promise on someone else's behalf, and a mother's portrait which does not look very much like either of her children, though it's very like the mother.
Plus a spoilerish observation:
I have heard people observe that in some respect, it is a Gothic novel, if you don't make Catherine's mistake about the heroine. Eleanor's life is rather closer to the typical Gothic novel than Catherine's.