What a remarkable book! I didn't pay any attention to the dates at the beginning of chapters until it became clear that they really did mean something! There were two distinct time periods whose relationship to each other were quite important. And after I figured out that it really was two separate timescales, things fell more into place.
I'm not sure what this the main character was Andrea or Laura; both of them were critical to the story and were both quite important to any and all preceding – and subsequent happenings. And the psychological trials to which Andrea was subjected were both thrilling and captivating; she and the readers were kept guessing and wondering throughout. I need to look for more books by Karin Slaughter. She clearly has a way with stories and twists that is capable of holding interest!