The gem leads Pendergast to an abandoned mine on the shore of California's Salton Sea, which in turn propels him on a journey of discovery deep into his own family's sinister past. But Pendergast learns there is more at work than a ghastly episode of family history: he is being stalked by a subtle killer bent on vengeance over an ancient transgression. And he soon becomes caught in a wickedly clever plot, which leaves him stricken in mind and body, and propels him toward a reckoning beyond anything he could ever have imagined . . .