![Digital Fortress](http://monsterbookshop.co.uk/cdn/shop/files/9780552151696.jpg?v=1713979423&width=1445)
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.