The Sign of the Four

"The Sign of the Four", also known as "The Sign of Four", is the second full-length novel in the Sherlock Holmes series by Sir Arthur Conan Doyle, first appearing in Lippincott's Monthly Magazine in February 1890 and published in book form later that year. The story is set in 1888 and begins with Miss Mary Morstan seeking the assistance of Sherlock Holmes regarding the mysterious disappearance of her father, Captain Arthur Morstan, and a series of anonymous annual gifts of valuable pearls she has received. The investigation quickly uncovers a convoluted plot involving a hidden treasure from India, the Indian Rebellion of 1857, and a secret pact made among four convicts—Jonathan Small, Mahomet Singh, Abdullah Khan, and Dost Akbar—along with two corrupt prison guards. The pursuit of the antagonists, including the peg-legged Jonathan Small and his Andamanese accomplice, Tonga, culminates in a dramatic chase along the River Thames.

This novel holds significant importance within the Sherlock Holmes canon. It is notable for the romantic subplot involving Dr. John Watson and Mary Morstan, leading to their eventual marriage. The narrative also provides further insight into Sherlock Holmes's character, depicting his use of cocaine when not intellectually stimulated by a case, and further showcasing his formidable powers of deduction and forensic methods. The story explores themes of greed, betrayal, and the complexities of justice, highlighting the corrupting influence of wealth and the far-reaching consequences of past actions.