Lewis and Clark have attained a mythic status in American history as our daring explorers of the frontier. That’s why it is so weird to have them show up again — sort of — in “The Dead Lands,” Benjamin Percy’s new post-apocalyptic novel. The author of the werewolf thriller “Red Moon” and the gothic eco-thriller “The Wilding,” Percy joins a parade of contemporary writers slouching toward dystopia.

About the time of our present age, somebody sneezed and blew up the world. As an influenza pandemic began wiping out cities, the mad response of governments was to launch nuclear missiles to contain the disease. In St. Louis, the citizens erected walls around the downtown area, creating the Sanctuary, and thought themselves to be the only survivors.

One of the great joys of the novel is Percy’s world-building, creating a future that is recycling its past. The story opens 150 years from that biological meltdown. There is no television, no Internet. Newspapers are kaput. When gasoline ran out, people resorted to riding horses, and a kind of retro economy sprang up with blacksmiths and apothecaries and dominated by tight controls on the rapidly dwindling water supply. Ruled by a tyrannical mayor who tolerates no dissension, the Sanctuary is a little fascist kingdom of fear. Beyond the walls are the Dead Lands, inhabited only by creatures mutated by decades of fallout: hairless sand wolves, giant spiders and albino bats.

And then from the West, a rider arrives at the gates. Dark-eyed and mysterious, she is called Gawea, and she brings news of a better world, where the rain falls and fresh crops grow, where civilization has been restored. A band of pilgrims, inspired by her story, decides to follow her back to the promised land. They are led by Lewis Meriwether, whose name is one of the many tweaks to distinguish the fictional from the historical. He is curator of the Sanctuary’s museum and inventor of extraordinary mechanical devices, including a flying metal owl, which unfortunately calls to mind the annoying bird from Ray Harryhausen’s stop-action movie “Clash of the Titans.” His partner in this adventure is Wilhelmina Clark, and they are joined by a small group who also share the names of some of the members of the original Corps of Discovery. History geeks will surely recognize Reed, York, Jon Colter and the rest as they follow the trail more or less of the 1804 expedition, bound for Oregon.

The real Lewis and Clark dog the fictional ones in “The Dead Lands,” but if some allegory is at work, I can’t find it. Percy, who grew up in Oregon , seems merely to be riffing on a favorite story. But ultimately the associations are a distraction, which is a shame, really, because otherwise the novel is finely crafted and relentlessly inventive.

“The Dead Lands” by Benjamin Percy. (Courtesy of Grand Central)

Percy writes with a strong line, his rhythms incantatory and musical. The book crackles with action and adventure, and his descriptions of the wonders and disasters along the trail are as vivid as any accounts from the Corps of Discovery journals. Take, for example, this passage: “They surprise a huddle of javelinas, the big bristly pigs snorting and squealing, rushing toward them and hoofing up a big cloud of dust and swinging their tusks from side to side, and Clark drops two of them with arrows before the drove escapes.” A subplot set back in the Sanctuary, where two children scheme to overthrow authority, balances neatly against the episodes from the westward expedition and is unburdened by any parallels to history.

“The Dead Lands” begins in darkness but ends in hope. Along the way, this band of survivors deals with brutality and violence, but also displays the fortitude and immensity of the human spirit touched by the natural world. When the true Corps of Discovery reached the Pacific, William Clark wrote, “Ocian in view! O! the joy.” Like the journals, “The Dead Lands” will often take your breath away.

Washingtonians, particularly those involved with the federal government, will be surprised by who saves the world and by a brief epilogue that features more echoes of American history. It’s downright Jeffersonian.

Keith Donohue is a novelist whose latest book is “The Boy Who Drew Monsters.”

THE DEAD LANDS

By Benjamin Percy

Grand Central. 400 pp. $26