Why does Catherine suspect General Tilney of murder?

Catherine imports Radcliffe plots into a ordinary abbey. Mrs Tilney died naturally; General’s grim manner and forbidden rooms trigger Catherine’s fantasy that he murdered her. Henry Tilney’s rebuke in the abbey — chastising her for applying fiction to his family — is Austen’s thesis on Reality vs. Imagination.

General is emotionally abusive and mercenary, not a Gothic villain with a corpse in the cellar. Satire of Gothic Novels requires Catherine’s error for comedy and growth. Evidence mid-novel Northanger chapters. Link who Catherine is and Henry’s role as educator. Coming of Age means accepting mundane cruelty over imagined horrors.