The Sign of the Four

A mysterious disappearance, a pact between four men, and a stolen treasure from India form the backdrop of this complex mystery. Mary Morstan asks Holmes to investigate the annual delivery of a perfect pearl, leading the duo into a chase across London and down the Thames. The story introduces the irregularities of Holmes's character, including his drug use, while weaving a tale of colonial greed and betrayal. It is a dark, atmospheric adventure that solidifies the bond between Holmes and Watson.