When the NSA's invincible code-breaking machine encounters a mysterious code it cannot break, the agency calls its head cryptographer, Susan Fletcher, a brilliant, beautiful mathematician. What she uncovers sends shock waves through the co r rido r s of power. The NSA is being held hostage--not by guns o r bombs -- but by a code so complex that if released would cripple U.S. intelligence. Caught in an accelerating tempest of secrecy a nd lies, Fletcher battles to save the agency she believes in. Betrayed on all sides, she finds herself fighting not only fo r her country but fo r her life, a nd in the end, fo r the life of the man she loves.