The Obsidian Chamber (Special Agent Pendergast Series #16)

A TRAGIC DISAPPEARANCE
After a harrowing, otherworldly confrontation on the shores of Exmouth, Massachussetts, Special Agent A.X.L. Pendergast is missing, presumed dead.
A SHOCKING RETURN
Sick with grief, Pendergast's ward, Constance, retreats to her chambers beneath the family mansion at 891 Riverside Drive—only to be taken captive by a shadowy figure from the past.
AN INTERNATIONAL MANHUNT
Proctor, Pendergast's longtime bodyguard, springs to action, chasi…