In 1785, Professor Sebastian Grave receives the news he fears most: the terrible Beast of Gévaudan has returned, and the French countryside runs red in its wake.

Sebastian knows the Beast. A monster-slayer with centuries of experience, he joined the hunt for the creature twenty years ago and watched it slaughter its way through a long and bloody winter. Even with the help of his indwelling demon, Sarmodel – who takes payment in living hearts – it nearly cost him his life to bring the monster down.

Now, two decades later, Sebastian has been recalled to the hunt by Antoine Avenel d’Ocerne, an estranged lover who shares a dark history with the Beast and a terrible secret with Sebastian. Drawn by both the chance to finish the Beast for good and the promise of a reconciliation with Antoine, Sebastian cannot refuse.

But Gévaudan is not as he remembers it, and Sebastian’s unfinished business is everywhere he looks. Years of misery have driven the people to desperation, and France teeters on the edge of revolution. Sebastian’s arcane activities – not to mention his demonic counterpart – have also attracted the inquisitorial eye of the French clergy. And the Beast is poised to close his jaws around them all and plunge the continent into war.