Relentless phone calls interrupt the peace of a warm August morning in the small village of Three Pines in Quebec. Someone has managed to track down Armand Gamache, head of homicide, as he sits with his wife in their back garden. When he finally answers the call, his rage shatters the calm of their quiet Sunday morning.

That's only the first in a sequence of strange events that begin The Grey Wolf. At first they seem small - a missing coat, a note for Gamache reading "this might interest you", a puzzling scrap of paper with a mysterious list - but then a murder. All propel Chief Inspector Gamache and his team toward a terrible realization. Something much more sinister than any one murder or any one case is fast approaching. A threat unlike anything they've seen before.