Used Book – Digital Fortress, Dan Brown

At the National Security Agency, the unbelievable is happening. TRANSLTR, the powerful decryption computer, cannot decipher a new code. Called to the rescue, Susan Fletcher, the beautiful and brilliant cryptanalyst, understands that a terrible threat hangs over all levels of power. The NSA is being held hostage by the inventor of an unbreakable encryption that, if released onto the market, would shatter the entire American intelligence system! Swept into a whirlwind of secrets and deception, Susan fights to protect her country and free the agency from this trap.

Soon betrayed by everyone, she will have to defend her own life as well as that of the man she loves.