The Valley of Fear - Arthur Conan Doyle - Bookniverse

The Valley of Fear tells a story of a murder mystery which seems insoluble. Sherlock Holmes was struggling to decode a letter when he received a notification of another murder. The deceased and the sender of the coded letter have quite a connection. The murder not only involves the head of an international crime syndicate, but also a major incident that happened in the United States more than a decade ago.