“Underground Airlines,” the new book by Ben H. Winters, is an alternate-history novel with a terrifying conceit at its heart. The book is set in a country that largely resembles the contemporary United States. There are references to CNN, search engines, Starbucks and UPS, but there is one significant difference: In Winters’s novel, slavery is still legal in a quartet of Southern states: the Hard Four as they are known. Abraham Lincoln was assassinated before taking office; the Civil War never happened; and “the great moral wrong” was allowed to persist through legislative compromise. The United States is now a pariah nation, the recipient of economic sanctions from Europe and Japan. Even in the “free” North, segregation remains. Black hotel guests are required to sign a register for the “guests of color.”

"Underground Airlines" by Ben Winters (Mulholland)

The book’s narrator and protagonist, Victor, is himself an escaped slave, who, at the age of 14, fled the slaughterhouse where he had been born and raised in bondage. After several years of liberty in the North, he was captured by federal law enforcement under the Fugitive Persons Law, a latter-day version of the Fugitive Slave Act. Instead of returning Victor to his owner, the feds trained him to be a “soul catcher” — an undercover operative working for a clandestine branch of the U.S. Marshals Service. His job is to hunt down runaway slaves, and Victor has proved to be very skilled at it. Over the course of his career, he has aided the capture of 209 escapees. In short, his continued enjoyment of what he calls the “miracles of freedom” is predicated on denying those miracles to others.

Victor copes with the horror of his job through disassociation and dehumanization. “I was not a person but a manifestation of will. I was a mechanism — a device,” he tells us early on. But beneath this self-justifying rhetoric is a more complex truth. Victor is a haunted, conflicted man, whose own escape was abetted by a murder. “I remember them all,” he says of the runaways he’s captured. The novel becomes the story of Victor’s attempt at redemption.

The book opens in Indianapolis, where Lincoln was assassinated and where Victor has come in pursuit of “a peeb” (i.e., a Person Bound to Labor) known by the code name Jackdaw. Jackdaw was enslaved in a textile plantation in Alabama owned by a vast corporation called Garments of the Greater South. (Winters brilliantly and horrifyingly imagines how the pairing of corporate capitalism and slavery might look in the modern era.) Jackdaw has escaped with the help of the Underground Airlines, a modern continuation of the Underground Railroad, but there are hints in his case file and elsewhere that he is not just another runaway slave.

I can’t say too much more without spoiling the plot, but the deeper Victor digs, the more apparent it becomes that Jackdaw’s fate is bound to his own and also to a secret that, if exposed, could lead to the eradication of slavery. A little past its halfway point this novel takes a surprising, but wholly necessary turn, directing Victor and the reader straight into the darkness that persists in those four slaveholding states.

The author Ben Winters (Nicola Goode)

Winters has won both an Edgar Award and a Philip K. Dick Award for books in his Last Policeman trilogy, which follow a New Hampshire detective as he investigates a series of crimes in the months before an extinction-level event: an asteroid colliding with Earth. Like “Underground Airlines,” the Last Policeman books offer an appealing hybrid of the best of science fiction and crime fiction, genres that have often been venues for writers to address themes considered too provocative or dangerous for mainstream culture. In that regard, it may be more accurate to say that “Underground Airlines” honors its genre antecedents by presenting us with an unexpected way of looking at the history of race relations in this country. The novel succeeds so well in part because its fiction is disturbingly close to our present reality.

The one facet of Winters’s alternate history that does not feel fully realized is its rendering of popular culture. The author has opted to include references to familiar names — Michael Jackson, Zora Neale Hurston, Norman Rockwell — but has altered their biographies in important ways. James Brown, we’re told, was a slave, forced to perform in the North, until he escaped to Canada. In comparison with the novel’s thought-provoking “what-if” speculations on American history and economy, these cultural re-imaginings feel contrived and unnecessary. But they are only slightly distracting. With “Underground Airlines,” Winters has written a book that will make you see the world in a new light.

Jon Michaud is a writer in New York.

Ron Charles is on vacation.

Underground Airlines

By Ben H. Winters

Mulholland. 327 pp. $26