When the United States' National Security Agency's code-breaking machine encounters a mysterious and ingeniously complex code called Digital Fortress that it cannot break, the agency calls in Susan Fletcher, a brilliant mathematician and their head cryptographer, to crack it. Susan, along with her fiancé, David Becker, a skilled linguist with eidetic memory, are thrust into a global chase that takes them from Washington, DC to the towers of Tokyo , where they must find a way to stop the spread of the code.
