Deliver Us From Evil by David Baldacci is an excellent thriller, and apparently the second book about secret government operative Shaw.
In this outing, Shaw runs into a private group who is killing Nazi survivors. He meets Reggie and her crew while they are working and the plan goes wrong but he's there to help.
Now Shaw, Reggie and her crew are up against the name who was the actual real Butcher of Kiev and the meanest more despicable person on the earth. He is truly evil. And vile.
This is an excellent thriller and in some spots, it's a rough read with the violence and gruesome torture methods explained in the pages.