THE SIGN OF FOUR by Arthur Conan Doyle
12 parts Complete Miss Mary Morstan arrives at 221B, Baker Street to request help with the mystery of her missing father, her anonymous gifts of pearls and a letter requesting her to meet an unknown person that evening.
First published in the Lippincott�s Magazine, Philadelphia and London, in February 1890. First book edition by S. Blackett in Oct. 1890