Sherlock Holmes has come into possession of a pack of cards that once belonged to his diabolical nemesis Professor Moriarty, but what secrets do they hide? Readers can join Sherlock and his loyal companion Dr. John Watson as they attempt to solve the puzzles concealed within and discover what Moriarty has truly hidden inside. Each conundrum on the cards corresponds to a narrative puzzle in the book. Readers may attempt to solve the card alone or read the story to gain a hint or two to help you along the way. With mathematical mysteries, hidden messages, and all manner of clever conundrums to solve, this addictive game will appeal to puzzle-lovers and Sherlock fans alike.