Reading this has been one of the most enjoyable reads I have had in a long time. It was not an easy read. It is a great psychological thriller, but it was not formulaic (which is why it was not an easy read).
You know from the prologue that one of the main characters is killed, and you know who did it. The first half of the book is spent building up to that murder. The second half of the book is spent looking at its consequences.