This is the secong in the Atlee Pine series. Pine is an FBI agent stationed at Shattered Rock, AZ. In this book she has been 'encouraged' to take some time off after stopping and somewhat abusing a pedophile who has just kidnapped a young girl.
Pine decides to go back to where she lived for a while which is Andersonville, Georgia, home of the infamous Civil War prison. When she lived there someone kidnapped her twin sister and nearly killed Atlee when they were 6 years old. Atlee wants to investigate that 30 year old crime and starts doing so.
As expected a whole can of worms is turned over and the story goes in a lot of directions. There is no shortage of bad guys and gals.
This is Baldacci's latest and it is a very good book.