A Fatal Grace (Dead Cold), by Louise Penny, is the second (2007) novel in the Three Pines Mysteries series, which feature Inspector Armand Gamache.

CC de Poitiers, a sadistic socialite, is fatally electrocuted at a Christmas curling competition in the small Québécois town …

CC, who had a “spiritual guidance” business based on eliminating emotion, was hated by seemingly everyone, including her husband, lover, and daughter. …

There is NO WAY I could guess the murderer. Great writing. And very complex.

Chief Inspector Gamache tells new agents four sayings that can lead to wisdom – four sentences his own mentor taught him:

I was wrong
I’m sorry
I don’t know
I need help