The "Norbury" Safeword

One of the most popular book anecdotes shared online comes from The Adventure of the Yellow Face. In this story, Holmes completely miscalculates, gets the entire theory wrong, and the mystery resolves itself without him. Humiliated, Holmes tells Watson: "If it should ever strike you that I am getting a little overconfident... kindly whisper 'Norbury' in my ear." Fans love bringing this up to prove that Holmes wasn't a perfect, unfeeling machine.