The Sign of Four by an author
Sherlock Holmes is bored and case-less, and relieving his boredom by alternating morphine and cocaine. Enter the charming Miss Mary Morstan, with whom Watson is instantly smitten. She requests the assistance of Holmes and Watson to solve the mysterious disappearance of her father, and the subsequent invitation to 'have justice' by an anonymous letter writer. Holmes and Watson happily accompany her to see the anonymous letter writer; only to become deeply embroiled in a mystery concerning treasure, murders, India, escaped convicts and small savages with poisoned blowpipes.