A. Conan Doyle 
A Study In Scarlet 

"A Study in Scarlet" is a detective novel written by Sir Arthur Conan Doyle. The book is the first in the Sherlock Holmes series and introduces the iconic detective and his loyal companion Dr. John Watson. The story begins with Dr. Watson returning from the war in Afghanistan and looking for a place to live in London. He is introduced to Holmes, and the two quickly become friends. Their first case together involves the mysterious death of a man found in an abandoned house. The clues lead them on a complex investigation that takes them from London to the American West. The book is divided into two parts, with the first part detailing the investigation and the second part revealing the backstory of the murderer. This book is known for its intricate plot and attention to detail, as well as its vivid descriptions of Victorian London and the American West.