"Susan is one of the top Code breakers at the NSA. She monitors the use of the code breaking machine that can break all codes in less than 3 hrs and is used by all forms of US intelligance. She is called in when a program is still running after 12+ hrs. At the same time her fiance is sent to Spain to try and locate the "key" to stopping the release of a code program that will allow the NSA to break codes that Digital Fortress (the encrypting program) is used to protect. In Spain it becomes clear that someone is out to keep the key safe as people who have come in contact with it are killed.
The story follows the progress to not only figuring out who has planted the code but how to keep it from letting the world into the NSA files."