When the Nsa's Invincible Code-Breaking Machine - Encounters a Mysterious Code It Cannot Break, the Agency Calls in Its Head Cryptographer, Susan Fletcher, a Brilliant and Beautiful Mathematician. What She Uncovers Sends Shock Waves Through the Corridors of Power. the Nsa is Being Held Hostage...Not by Guns or Bombs, but by a Code so Ingeniously Complex That If Released It Will Cripple U.S. Intelligence.