Book excerpt: This harrowing tale of survival pays moving tribute to the courageous British sailors of World War II, and offers entrance into the ultra-secret world of British code-breaking. In November 1941, the British light cruiser "HMS Dunedin" was patrolling the shipping lanes of the central Atlantic, directed to its targets by British intelligence agents who had cracked the German "Enigma" code. On November 24, a torpedo from a German U-boat sent her crashing to the ocean floor, along with over 400 of her crew. For three days, 72 desperate survivors clung to the flotsam, fighting off swarming sharks and pounding waves until an American ship stumbled across the scene.