'There's a body in Lost Nation.' But the line goes dead before Chief Inspector Armand Gamache can question the caller. The head of homicide for the Sûreté du Québec has no idea where Lost Nation is, or who woke him in the small hours of the morning at his home in Three Pines. What he does know is that the man was terrified.

When he and his team of Jean-Guy Beauvoir and Isabelle Lacoste find both place and body, the situation only grows more bizarre. The unidentified dead man appears to be from an era more than a century old. He's lying in a long-abandoned cemetery, on top of a grave with a date, but no name.

Adding to the mystery, the early morning call appears to have come from Gamache's friend and neighbour, Clara Morrow. While she denies any knowledge of it, it becomes clear there is some connection between her, the Morrow family, and Lost Nation.

Soon, Gamache and his team are faced with tracking down not just the legend of Lost Nation, but a lost ship, lost documents belonging to an eccentric Victorian botanist, and a mysterious plant not seen in a century, that might save, or take, countless lives.

As the ghosts begin to gather, Gamache realises that the body on the grave is far from the only death. To solve the crime and avert catastrophe he must look to rancid secrets and old lies no longer dead and buried.