First book of who would be one of the most famous detectives of all time, prototype of those who came next. The novels starring Sherlock Holmes are set in a police genre, in which investigation, suspense and even some supernatural fantasy are mixed. Our protagonist always studies the mysteries that seem impossible, finding the logic where there seemed not to be any. In this, his first case, a person is killed in London, but what seems to be a murder like any other, it is a problem that have its origins in the Mormons and some characters of this denomination who live in the United States. Throughout the investigation he will be accompanied by Dr. Watson, who is the narrator of the story.