Excellent writing and gripping plot, as usual.
Two flaws. Daniel's hatred of his father, Gamache, is unrealistic in an adult son who had two strong parents and a stable middle class family life. Suggesting Daniel could be so damaged because his parent was a cop is an insult to all children who grew up with parents in the military or police force of any other dangerous profession.
And the end moves too fast. I had to re-read the last chapters again to understand what exactly had happened.