"A Observation of the Red Chain" by Arthur Conan Doyle is the first book in which the great detective Sherlock Holmes appeared. In this gripping novel, Holmes and his loyal friend and roommate, Dr. Watson, investigate an intricate crime in London. The book captivates the reader not only with a non-trivial plot and unpredictable development of events, but also with vivid and memorable characters. "A Observations on the Red Chain" is a masterpiece of the detective genre, which remains relevant and fascinating even today.