Obsidian Chamber (Agent Pendergast Series, 16)

A TRAGIC DISAPPEARANCEAfter a harrowing, otherworldly confrontation on the shores of Exmouth, Massachusetts, Special Agent A.X.L. Pendergast is missing, presumed dead.A SHOCKING RETURNSick 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 MANHUNTProctor, Pendergast's longtime bodyguard, springs to action, chasing Constance's kidnapper through cities, across oceans, and into wastelands unknown.BUT IN A WORLD OF BLACK AND WHITE, NOTHING IS AS IT SEEMSAnd by the time Proctor discovers the truth, a terrifying engine has stirred-and it may already be too late . . .