Mark Allen Smith clearly likes to take chances. In his remarkably assured first novel, “The Inquisitor,” he introduces one of the most unsettling, potentially alienating creations in recent popular fiction: a professional torturer. With unobtrusive skill, Smith transforms this unpalatable material into a swiftly paced narrative as disturbing as it is compelling.

The novel’s eponymous protagonist is Geiger, a man with no first name, no known past and a gift for the art of “information retrieval.” Geiger is a human cipher who came to consciousness, a fully formed adult, aboard a Greyhound bus in New York’s Port Authority terminal. He was, at the moment of his awakening, no more than “a scarred, aching body with an unencumbered mind, a human machine without a memory card.” In the years since, he has invented himself from scratch, constructing a lucrative career out of two interrelated talents: an uncanny ability to distinguish truth from falsehood and a bone-deep understanding of the variety and uses of pain. Acting on behalf of wealthy and ruthless clients, he tortures people for money, extracting whatever information those clients require. At the same time, Geiger maintains a strict personal code, refusing to ply his peculiar trade on children or on those too old or infirm to withstand the rigors of interrogation.

In the opening pages, Smith offers a pair of brief, chilling glimpses into Geiger’s working life. With clinical detachment and practiced skill, the man known as “the inquisitor” utilizes a precise combination of physical and psychological torment to break down the resistance of two recalcitrant subjects, one of them a ferocious and almost fearless mafia hit man. Mixed in with these grim scenarios is an equally grim reflection on the history and evolution of torture over the past several hundred years. By the time these grisly preliminaries have concluded, the reader is firmly, if uncomfortably, ensconced in Geiger’s world.

The ensuing narrative encompasses a host of players and a multitude of twists, turns, reversals and betrayals, all in the service of a single, central story: the disruption of Geiger’s carefully ordered, misanthropic life. That disruption arises out of two very different sources, the first of which is internal. Geiger has begun to experience recurring dreams that feature a looming male figure, with images of danger and bodily disintegration. These dreams are the subterranean rumblings of a deeply buried past struggling to make itself visible. The second source emerges when a duplicitous client delivers a 12-year-old boy for interrogation. Refusing to violate his moral code, Geiger rescues the boy from his captors and heads for safety, leaving chaos — and a shattered career — in his wake.

What follows is a nicely orchestrated chase sequence, in the course of which a number of revelations — some personal, some political — gradually surface. Participants include Geiger’s business partner and research assistant; the partner’s sister, a mental patient with undisclosed traumas; a trio of operatives from a clandestine government agency; a treacherous mafia don; a rival torturer; and a whistleblower with an urgent agenda. At the center of this — the MacGuffin that drives the plot — is a set of computer discs that contain an explosive and dangerous secret touching upon the debate about torture that arose during the George W. Bush administration and continues to this day.

“The Inquisitor: A Novel” by Mark Allen Smith (Henry Holt & Co.)

Much credit goes to Mark Allen Smith for placing such an inflammatory subject front and center in this absorbing, highly accessible novel. Without flinching from or minimizing Geiger’s very real atrocities, Smith manages to locate the man’s nascent humanity. Should Smith decide to revisit these characters in the future — and internal evidence suggests that he might — the focus, I suspect, will shift from the brutal realities of torture to two of its more benign offshoots: guilt and expiation. That would be an imaginative journey well worth following. But whatever does or doesn’t happen in subsequent volumes, “The Inquisitor” is an auspicious and provocative beginning.

Sheehan is the author of “At the Foot of the Story Tree: An Inquiry into the Fiction of Peter Straub.”

The Inquisitor

By Mark Allen Smith

Henry Holt.
324 pp. $27