When scouring the population for codebreakers, Bletchley Park recruiters devised ingenious mind-twisters to assess the puzzle-solving capacity of candidates for Britain's elite WWII-era codebreaking team. This collection of cryptic crosswords, secret languages, and complex riddles contains the original puzzles used by Bletchley Park to identify the individuals who would eventually defeat Germany's Enigma machine. Paperback, 280 pages.