A Study in Scarlet: A Sherlock Holmes Novel (Unabridged‪)‬

The story begins in 1881, when Dr. Watson, having returned to London after serving in the Second Anglo-Afghan War, visits the Criterion Restaurant and runs into an old friend named Stamford, who had been a dresser under him at St. Bartholomew's Hospital. 

Watson confides in Stamford that due to a shoulder injury he sustained at the Battle of Maiwand, he has been forced to leave the armed services and is now looking for a place to live. Stamford mentions that an acquaintance of his, Sherlock Holmes, is looking for someone to split the rent at a flat at 221B Baker Street, but he cautions Watson about Holmes's eccentricities.

The book's title derives from a speech given by Holmes, a consulting detective, to his friend and chronicler Watson on the nature of his work, in which he describes the story's murder investigation as his "study in scarlet": "There's the scarlet thread of murder running through the colourless skein of life, and our duty is to unravel it, and isolate it, and expose every inch of it."