The first story of the legendary detective Sherlock Holmes and his friend Dr. Watson, a military surgeon who returns to London after his participation in the war. Watson and Holmes move to the famous 221B Baker Street. Where Watson faces the eccentricities of Holmes and his magical ability for the deduction. In this opportunity Holmes is called to solve a strange murder: a deserted house, a corpse without wounds, a mysterious phrase written with blood on the wall, Two officers from Scotland Yard they have no clues. This fascinating story. It is an indispensable piece of the work is Conan Doyle. Not only because he introduces us to his two fundamental characters. Sherlock Holmes and Dr. Watson. If not because it exposes the scientific method followed by Holmes based on logic and in the powers of observation and deduction.