In "The Case-Book of Sherlock Holmes," Arthur Conan Doyle crafts a suspenseful narrative where Sherlock Holmes employs his keen observational skills to decipher the truth behind a complex case. The quote, "If you had killed Watson, you would not have got out of this room alive," is a reflection of Holmes' deep bond with his friend and companion, Dr. John Watson. It also emphasizes Holmes' quick wit and the protective instinct he feels toward Watson, showcasing their strong partnership in the face of danger.

This statement underlines the gravity of the situation and serves as a reminder of the loyalty and camaraderie between Holmes and Watson. The phrase highlights Holmes' capability to not only deduce the motives of others but also to predict their potential reactions in tense situations. It exemplifies the blend of intellectual prowess and emotional connection that characterizes Doyle's famous detective stories.