The intellectual's Stephen King, Pyper lifts a tale of the impossible to the realm of waking nightmare. Evil shadows a frantic journey by demonologist David Ullman of Columbia University to recover his lost daughter, Tess. Given his lifelong study of good and evil via John Milton's Paradise Lost, the professor is both troubled and intrigued when invited to travel to Venice to witness an event, oblivious to the fact that he will forfeit his twelve-year-old daughter to the forces of evil coercing his cooperation.

The decision is made easy when David's wife informs him that she is leaving him for another man, and his dearest friend, psychologist Elaine O'Brien, shares her own tragic news. O'Brien, also a professor at Columbia, has become David's most trusted confidante, and he is devastated by the information she shares. Impulsively, father and daughter embark on a journey to the historically corrupt city of Venice, where David will be profoundly shaken by what he witnesses and Tess will fall from the top of a high building, just out of her father's grasp.

Thus begins David's quest to recover his daughter, hostage to another dimension, who can be saved only by extraordinary means before the next full moon. Only by surviving a number of challenges by his tormentor can he ascertain what "the Unnamed" truly expects in exchange: the fruit of the witnessed event, an "apocryphal document of demonic activity" caught on film in a camera that has been provided for him. Only David's conviction that Tess is not truly gone allows him to endure the barrage of encounters as he travels back to Manhattan alone and from there to the Midwest, an otherworldly journey conducted as much in the netherworld of the impossible as in real time.

It is on this metaphysical battleground that Pyper excels, the jousting field for the powerful forces of evil versus an agnostic's attempts to counter each thrust and find truth guised in deception. Humans take on the countenances of the dead, the landscape strewn with reminders of dark forces absorbing the lives of unsuspecting victims as evil breaks through barriers of normalcy to leave chaos in its wake. A stranger's face becomes that of a Pursuer meant to follow David, torment him and ultimately deliver a painful ending.

Long shadowed by "the black dogs of unaccountable gloom," the territory he travels is not unfamiliar to Ullman (nor perhaps to Pyper), his childhood memories burdened with the drowning death of his brother and his father's pronouncement: "It should have been you." The breath-stopping breach between the possible and the impossible gives the novel its power, a never-ending nightmare become horribly real, though visible only to David, and to O'Brien when she joins him on the road. The evil is balanced by David's strength and the value of his cause, a resistance to the negation that surrounds and nearly overpowers him.

The rightness of David's argument lies in his inherent nobility despite his all-too-human flaws, his understanding of his adversary's methodical deception and a determination not to give up as long as there is hope for Tess. The grueling battle continues until the final page, when all is lost but more is gained.