Supernotes are counterfeit $100 bills, primarily in circulation in Asia and produced so superbly that they thwart even the most advanced detection methods. But the new book “Supernotes” takes that description even further: “Authentic bank notes, but printed in a place that’s not the U.S. Mint. And therefore false? No. Different. But real.”

The source of these counterfeit C-notes is central to this new thriller. But the story focuses more extensively on the detention, imprisonment and torture of an Italian man in a Cambodian prison. We follow his struggles to escape while his family’s attorney in Rome works to obtain his release. As the story shuttles between the horrors of prison life and the frustrations of legal maneuvering, it also weaves back and forth in time to reveal the prisoner’s history and the events that led to his incarceration.

The prisoner was posing as the co-owner of a bar in Phnom Penh, Cambodia, but he’s really Agent Kasper, who has worked with Italy’s national military police and the CIA. From the start, it’s hinted that a recent CIA mission in North Korea may have sparked his current troubles, but when representatives from the FBI and Homeland Security show up to get him released, Agent Kasper confronts them: “You’re the people who got me detained. . . . You’ve committed a crime. A very serious crime.”

The nature of the crime is withheld — artificially it seems, since the reader is otherwise privy to Agent Kasper’s thoughts — and dodging and delaying the truth about those supernotes seems part of the book’s unevenness, especially given the layering of flashbacks that give the whole story such a fitful structure.

But a bigger uncertainty surrounds the book’s own identity — wavering between its “thriller” subtitle and its “based on true events” tagline. Agent Kasper is both co-author and protagonist; the other co-author, Luigi Carletti, is an investigative journalist; and many of the “characters” in the book are real-life figures in international business and politics. But “Supernotes” situates itself as neither memoir nor exposé, and so the enormity of that central secret — allegations about international corruption and U.S. culpability — is undercut by blurriness about where fact ends and fiction begins.

Author Luigi Carletti. (Fabio Muzzi)

Possibly more troubling for readers is that the story’s “thriller” aspects seem muted. Its plot never fully takes off — perhaps it’s weighed down by facts? — and the resolution to Kasper’s crisis proves anticlimactic.

Seeming to hedge bets in both directions, “Supernotes” finds itself stuck in an uncertain and ultimately unsatisfying middle ground.

Art Taylor is a professor of English at George Mason University and the author of “On the Road with Del & Louise: A Novel in Stories.”