The air is unbearably tense as Armand Gamache returns to the Surete du Quebec for his first day of work since his demotion from its command to head of homicide.

Amid blistering personal social media attacks, Gamache sets out on his first assignment - to find a missing woman. But as he leads the search for Vivienne Godin, Three Pines itself is threatened when the river breaks its banks, and a province-wide emergency is declared.

As the waters rise, a body is discovered - and the victim's distraught father contemplates a murder of his own. As a father himself, Gamache is haunted by a question . . . what would he do, if his child's killer might walk free?