The Core Classics are generally considered suitable for fourth and fifth grade students. The texts are illustrated, annotated, and include a brief biography of the author.
At the time Sir Arthur Conan Doyle created Sherlock Holmes, the most famous detective in fiction, most stories were told in parts in magazines over many months. The problem with that, Doyle thought, was that if readers happened to miss the first part, they would not be interested in picking up the story later. So he decided to write stories that were complete in one issue and had main characters that reappeared in future adventures. Edgar Allen Poe wrote the first detective story, but Doyle reinvented it with the characters of Sherlock Holmes and Dr. John Watson.