One of the more memorable TV shows of my childhood was “The Millionaire.” In each episode, a fictional character received a million bucks, tax free, out of the blue. The drama, which ran from 1955 to 1960, centered on what the lucky stiff did with that windfall and how it changed his or her life. The donor, John Beresford Tipton — the best name for a plutocrat since Scrooge McDuck — withheld his identity from the recipient; the gift was supposed to be an anonymous rain of wealth, not an ego trip for the philanthropist.

Forrest Fenn, the real-life donor at the heart of “Chasing the Thrill,” Daniel Barbarisi’s rousing account of a 21st-century treasure hunt, was no John Beresford Tipton. Fenn very much wanted to be known, even idolized, as the burier of a chest containing gold coins, jewelry and other baubles with an estimated worth of at least $1 million. So vainglorious was Fenn that he sometimes showed up at Fennboree, the annual gathering held by seekers of his loot.

The fun — if that’s the right word for a contest that came to obsess many of its players — started in 2010, when Fenn, who had made his fortune as an art dealer in Santa Fe, was 80 years old. That year he published a memoir, “The Thrill of the Chase,” in which he mentioned having buried the chest “in the mountains north of Santa Fe”; later he expanded the searchable territory to include Colorado, Wyoming, and Montana while excluding “the parts of the Rocky Mountains that trickle into Canada, Idaho, and Utah.” (Lovers of the Canadian Rockies will surely take exception to Barbarisi’s reduction of that vast and breathtakingly beautiful range to a “trickle.”) Fenn strewed more clues in a poem he wrote, which featured stanzas like this:

Begin it where warm waters halt

And take it in the canyon down,

Not far, but too far to walk.

Put in below the home of Brown.

English literary critic William Empson gave the title “Seven Types of Ambiguity” to his classic analysis of how poems differ from, say, toaster-oven instruction manuals. Fenn’s doggerel had seven times seven types of ambiguity, enough to keep an estimated 100,000 fortune hunters poring over it for a decade. Unfortunately, some of them strayed into national parks, which, Barbarisi notes, “were suddenly overwhelmed, forced to create special announcements, rules, and cautions specifically for the brazen Fenn hunters as they tramped through protected wildlife zones and even dug up outhouses in search of Fenn’s ‘home of Brown.’ ”

Fenn glossed his poem so as to deflect people away from sensitive landscapes, but searchers got into trouble anyway, notably by following clues to spots where they faced a choice between fording a river in spate or backtracking for miles. Four Fennboys lost their lives, and the man himself admitted to Barbarisi, “Knowing everything I know now, I wouldn’t do it again.”

Barbarisi conducted much of his research accompanied by Beep, the handle of a chap who had mentored Barbarisi after the latter quit his reporting job at the Wall Street Journal in 2015 to write a book on fantasy sports. Although Beep had made a fortune playing those games “despite knowing virtually nothing about sports,” he proves to be an erratic treasure hunter, apt to follow up a brilliant reading of one line from Fenn’s poem with a tortuously forced reading of the next. More than once, Barbarisi must find a diplomatic way to let Beep know how daffy his latest take on a Fennian ambiguity appears to an outsider.

Barbarisi writes with gusto and portrays the eccentrics he encounters with a candor that never quite slips into mockery; he sums up Beep as “a Renaissance man of the frivolous.” He can also make a landscape come alive. I’ve read many descriptions of Yellowstone geysers, but none more striking than his evocation of how runoff from the Artemisia Geyser affects the immediate surroundings. “The ground itself was a chalk white, the liquid shimmering on it like mercury. Up close, the water running over the ground gave it a look like a shucked oyster, quivering before you slip it down your throat.”

Barbarisi, now a senior editor at the Athletic, occasionally gets too caught up in his subject. His chapter on searching for a very different kind of treasure — what lies in old galleons at the bottom of the ocean — runs on too long and probably should have been cut entirely. He is more judicious in covering the conspiracy theories hatched by disappointed seekers during the hunt and afterward, but let’s draw a veil over how the contest ended. You can find out online, of course, but Barbarisi tells the story so well that you should resist any form of peeking ahead and leave the matter in his capable hands.

Dennis Drabelle’s new book, “The Power of Scenery: Frederick Law Olmsted and the Origin of National Parks,” will be published in November.

Chasing the Thrill: Obsession, Death, and Glory in America’s Most Extraordinary Treasure Hunt

By Daniel Barbarisi

Knopf. 368 pp. $28