As the head of the FBI's Criminal Apprehension Unit, Dillon Savich has developed predictive analogue programs to aid in the capture of serial killers. Enter Lacey Sherlock, a very well-qualified new agent who seems bright and eager and on the up-and-up. But is she really?

When there's a vicious murder in Boston, she's off like a shot, lying to Savich. When Savich finds out what's going on, he realizes they'll all be in deep trouble, maybe even victims themselves, if he and Sherlock don't find out who murdered her sister seven years before....