With anti-mask vigilantes, the omicron virus and lost luggage, you already have enough to worry about when flying.

But here’s one more variant of concern: Before landing, you might be spontaneously duplicated.

That’s the mind-bending premise of France’s hottest novel, “L’anomalie,” by Hervé Le Tellier, a former science journalist and a member of experimental writing group Oulipo. Winner of the 2020 Prix Goncourt, “L’anomalie” has already sold more than a million copies in the author’s homeland, and now it arrives in the United States on a tail wind of international acclaim.

Make sure any carry-on expectations are placed completely under the seat in front of you. Although Americans are frustratingly xenophobic when they make reading choices, “The Anomaly,” translated by Adriana Hunter, could be the rare exception. It’s French, but not trop francais. The book’s intellectuality is neatly camouflaged by its impish humor. Indeed, with its elegant mix of science fiction and metaphysical mystery, Le Tellier’s thriller is comfortably settled in the middle seat between “Lost” and “Manifest.”

Much is left unexplained in “The Anomaly,” but all the characters agree on one thing: Their Air France flight from Paris to New York in the spring of 2021 is a nightmare. We witness that terror early in a chapter called “The Spin Cycle,” which is typical of the novel’s wit. Moments before beginning its descent, the Boeing 787 hits a spectacular storm. “There’s not just one anvil-shaped mesocyclone spiraling high up into the atmosphere,” Le Tellier writes, “but dozens of them, as if they were being lifted by an invisible hand, and all fusing together.” The pilot has only enough time to warn his passengers before the plane plummets into a pitch black vortex. “Those few seconds feel like an eternity, and then despite the tornado’s gusts, the plane finds a warm, rising current and a semblance of support, producing that intense crushing trough-of-a-roller-coaster sensation.” Screams fill the cabin.

Depending on your nerves, “The Anomaly” may not be the best book to read during your next flight. At the very least, every copy should come with an airsickness bag.

But rest assured that all the passengers survive this terrifying twirl in the sky. What’s waiting for them when they arrive, though, is even more alarming: The plane and everyone aboard it already landed almost four months earlier.

If you think it’s confusing that so many black carry-on bags look alike these days, just wait. A duplicate set of passengers on American soil would test any airline customer service department. In Le Tellier’s telling, this unprecedented situation presents the United States government with a national crisis. The military goes on high alert; the intelligence services spring into befuddled action. Are these clones an elaborate trick engineered by an enemy country, or do they represent a fundamental glitch in the space-time continuum?

None of the proposed explanations feels definitive, but the existence of these replicated people — out of sync by 106 days — calls into question the foundation of reality. “Conspiracy theories are proliferating,” Le Tellier writes. “When seven billion human beings find out that they may not really exist, it’s not easy to comprehend.”

Le Tellier has some fun contrasting the reactions on different sides of the Atlantic. “Media-savvy philosophers,” which are apparently a thing in France, analyze this extraordinary phenomenon on Paris talk shows. But in the United States, which is still bickering about climatology, evolution and even basic virology, fanatics panic and lash out violently. “Religion is a carnivorous fish in the abyssal depths,” Le Tellier writes with a heavy dose of his very French condescension. “It emits the feeblest of light and needs a vast darkness around it to attract its prey.”

But these broad bits of social and political satire — along with some silly drama involving emergency mathematicians — are the weakest elements of “The Anomaly.” (A scene showing a Trumpy American president struggling to understand string theory feels like shooting supernovas in a bucket.)

The novel soars, though, when it focuses instead on individual passengers from the Air France flight(s). In these chapters — each carefully dated to help us keep everyone straight — we see people struggling to comprehend this most incomprehensible moment of personal inflation. How, after all, would you react to meeting a duplicate of yourself — a person with exactly the same claim on your job, your possessions, your memories; and with exactly the same anxieties about meeting a duplicate? And would your spouse accept this new ménage à trois? It’s a predicament that gives a whole new meaning to Heather Has Two Mommies.

Le Tellier starts with an international assassin who’s already living with multiple identities. For him, the arrival of a doppelganger who literally knows where all the bodies are buried is a particularly alarming development. But even ordinary folks are discombobulated by meeting themselves in the flesh. And the four-month time lag between these molecular twins raises a whole other set of complications. Another man learns his double is dying from a disease he hasn’t been diagnosed with — yet. And a writer wonders why his double committed suicide.

In these clever stories and a handful of others, Le Tellier dares us to wonder if we could stand meeting the figure in the mirror. It’s what makes “The Anomaly” a flight of imagination you’ll be rolling over in your mind long after deplaning.

Ron Charles writes about books for The Washington Post and hosts TotallyHipVideoBookReview.com.

The Anomaly

By Hervé Le Tellier

Translated from the French by Adriana Hunter

Other Press. 391 pp. Paperback, $16.99