Arthur Conan Doyle's The Sign of the Four is a detective novel written in the late 19th century, featuring the legendary detective Sherlock Holmes and his loyal companion, Dr. John Watson. The story revolves around a complex mystery involving a missing treasure, the disappearance of a father, and a series of enigmatic pearls sent annually to a young woman. It masterfully combines elements of adventure, crime, and intrigue, showcasing Holmes’s extraordinary deductive reasoning.
The novel opens with Dr. Watson’s candid portrayal of Sherlock Holmes’s troubling habit, particularly his use of cocaine to stimulate his mind. Watson’s concern for Holmes’s health contrasts with the detective’s insatiable thirst for intellectual stimulation, highlighting the dynamics of their relationship.
The plot unfolds with the arrival of Miss Mary Morstan, who presents a peculiar case involving her father’s mysterious disappearance and the regular receipt of pearl gifts from an unknown sender. This introduction sets a suspenseful and curious tone, hinting at the intertwined fates of the characters and the thrilling investigation that lies ahead.

Chapter I. The Science of Deduction
Chapter II. The Statement of the Case
Chapter III. In Quest of a Solution
Chapter IV. The Story of the Bald-Headed Man
Chapter V. The Tragedy of Pondicherry Lodge
Chapter VI. Sherlock Holmes Gives a Demonstration
Chapter VII. The Episode of the Barrel
Chapter VIII. The Baker Street Irregulars
Chapter IX. A Break in the Chain
Chapter X. The End of the Islander
Chapter XI. The Great Agra Treasure
Chapter XII. The Strange Story of Jonathan Small