Sir Arthur Conan Doyle 
A Study In Scarlet [EPUB ebook] 

A Study in Scarlet is an 1887 detective novel written by Arthur Conan Doyle. The story marks the first appearance of Sherlock Holmes and Dr. Watson, who would become the most famous detective duo in popular fiction.
When a postwar search for London lodgings introduces ailing doctor John H. Watson to quirky chemist Sherlock Holmes, their collaboration in the art of observation and deduction begins. Congenial flatmates and even better colleagues, the pair is quickly drawn into a case of murder and revenge that has Scotland Yard at their wits’ end.
Although Conan Doyle wrote 56 short stories featuring Holmes, A Study in Scarlet is one of only four full-length novels in the original canon. The novel was followed by The Sign of the Four, published in 1890. A Study in Scarlet was the first work of detective fiction to incorporate the magnifying glass as an investigative tool.