The Penn Cage books by Greg Iles are a cracking series.
I’ve just finished reading the last 3 volumes, The Natchez Trilogy, which build to a superb climax. The series is based around Penn Cage, a lawyer in Natchez, Mississippi, uncovering the racial history of the south, the dark past of his home town and some secrets within his own family.
This is pacy, dark, tense reading and difficult to put down. If you like James Lee Burke (one of my top favourites) then you will enjoy this series. It’s worth starting at the beginning.