10 cases presented on a VHS video tape, each with 3 chapters. At the end of each chapter, each player has an opportunity to earn extra turns by correctly answering a Quick Quiz question about the chapter. A player's turn consists of either checking one of 20 location cards and getting a clue or acquiring either a Badge or Key Card. These cards are used to lock off clues from other players, or open locked clues. Further, you must possess a Badge Card before revealing the solution, and another player can stop you that turn by giving up their Badge Card. The first person to announce the right solution proves the equal of Mr. Holmes. - BoardGameGeek