Dr. Watson, who served in the English armed forces and was in the Afghan war, retires and returns to his homeland, in England. Since the financial situation of the doctor is very precarious, his long-time friend Mr. Stamford offers him to rent a room in the house at 221-B Baker Street, which is rented by an elderly lady - Mrs. Hudson. The second rented room is already occupied by another gentleman - the mysterious Mr. Sherlock Holmes. Holmes makes an ambiguous impression on Watson. He conducts complex chemical experiments with blood, plays the violin, has the deepest knowledge about cigar ash, London dirt and criminal law, but at the same time demonstrates complete ignorance of well-known truths (for example, the fact that the Earth revolves around the Sun), does not read fiction, as well as books on history and philosophy. At the same time, very strange visitors constantly come to Holmes, and on the table he has portraits of personalities of a disgusting appearance. Therefore, Watson begins to seriously suspect Holmes of involvement in the underworld.