Miss Mary Morstan contacts Sherlock Holmes for his help regarding her father, captain Morstan, who disappeared 10 years ago. Since his disappearance she annually receives a valua 　　Miss Mary Morstan contacts Sherlock Holmes for his help regarding her father, captain Morstan, who disappeared 10 years ago. Since his disappearance she annually receives a valuable pearl by post from an unknown person. The mystery leads Holmes and doctor Watson into an intricate plot regarding a lost treasure belonging to four convicts on the Andaman Islands 详情