Quinn Barry wants to be an FBI agent - someday. Right now she's just a nobody, a computer programmer toiling in a basement office, revamping ancient computer programming against impossible deadlines. Only, carrying out some routine maintenance on the FBI's new Combined DNA Index System - CODIS - Quinn finds a link between five unsolved crimes, a series of brutal murders that it has never matched before. Telling her boss of her discovery, however, has unexpected repercussions. Blamed for the 'error' and immediately reassigned to Quantico on what turns out to be little more than a routine upgrade, Quinn begins to suspect a more frightening scenario than a mere glitch in CODIS's programming. What if there is a serial killer at work whose activities have up to now been masked by the very system set up to detect him or her? Her suspicions cost Quinn her job, but that's the last thing on her mind as she finds her own life at risk. It's certain no one is going to believe that a 22-year-old computer clerk has unearthed one of the agency's darkest, dirtiest secrets - a US military machine prepared to overlook various character flaws in their key personnel, even psychopathic tendencies...