Sharpen your sluggish brain with 70 specially commissioned puzzles and challenges devised by Baker Street's legendary detective. Sherlock Holmes' famous sidekick and longtime friend, Dr John Watson, recounts the mental exercises Holmes conceived for him so that you too can strengthen your facilities for analysis, logic, reason, arithmetic, creative thought and deduction. These cunning puzzles have been grouped by their approximate difficulty but as a wise man once said, 'All questions are hard if you don't know the answer, and easy if you do.'