A seemingly straightforward private case turns out to be much more complicated-and sinister-than Special Agent A.X.L. Pendergast ever could have anticipated. Special Agent Pendergast and Constance Greene have been called to Exmouth, a small town on the wild Atlantic coast of Massachusetts, to investigate a seemingly innocuous theft. But what they discover at the crime scene changes the course of their investigation: a sealed burial chamber, complete with rusted leg irons, fragments of bone and claw marks on the inside-face of its bricks. Then a historian is found murdered in the desolate salt marshes that surround the town, his face mutilated, his body carved with arcane symbols. Exmouth has a grim history dating back to the aftermath of the Salem witch trials. And now a dark secret, centuries old, is rising to the surface.