The Final Problem
Doctor Watson, even when narrating, never meets Moriarty (only getting distant glimpses of him in "The Final Problem") and relies upon Holmes to relate accounts of the detective's feud with the criminal. Doyle is inconsistent on Watson's familiarity with Moriarty. In "The Final Problem", Watson tells Holmes he has never heard of Moriarty, while in "The Valley of Fear", set earlier on, Watson already knows of him as "the famous scientific criminal".