A Study in Scarlet by Arthur Conan DoyleHolmes explains the significance of bloodstains as evidence in criminal trials. After Stamford introduces Watson to Holmes, Holmes shakes Watson's hand and comments, "You have been in Afghanistan, I perceive." Though Holmes chooses not to explain why he made the comment, Watson raises the subject of their parallel quests for a place to live in London, and Holmes explains that he has found the perfect place in Baker Street. At Holmes's prompting, the two review their various shortcomings to make sure that they can live together. After seeing the rooms at 221B, they move in and grow accustomed to their new situation.