Meg Parrish, a cryptographer for NSA's Central Security Service in Portland, Oregon, is both brilliant and troubled. Gifted in her ability to recognize and decipher codes, she is also a woman haunted by a history of tragedies which have occurred at five-year intervals throughout her life. While working undercover at a software engineering firm, Meg manages to break through a series of passwords and retrieve a set of codes that might affect national security. Unknowingly, she has set in motion a series of events that sends her running for her life. As she seeks the truth about the codes, the hunt leads her from Portland to San Francisco and on to Albuquerque. Along the way, she must not only discover the forces that want these codes, but she must overcome the nightmares from her past.