After a brief idle spell, Fleming found work at the Spectator. At the time, the long-lived weekly magazine was known for its sterling reputation, but not for its editorial energy. The job turned out to be an awkward fit. Hart-Davis writes that Fleming “began producing articles of such incisive wit and cynicism that the older hands on the paper became seriously alarmed.” His bosses were perhaps relieved when Fleming informed them that he had been selected as an honorary secretary for a British trade mission to China, and would require a four-month leave of absence. He returned to England the next year and resumed his blithe assault on the Spectator’s masthead, inventing a contributor named “Walter B. Tizzard” and using the name to sign a series of opinionated reviews. But the China trip made him hunger for more adventurous pastimes.

And so he devoured a notice in the Times of London in April 1932, promising adventure and amusement in the wilds of Brazil. “It is easy to attract public attention to any exploit which is at once highly improbable and absolutely useless,” wrote Fleming. The advertisement, which ran in the paper’s “Agony Column” devoted to missing relatives and friends, seemed to fall into both categories: “Exploring and sporting expedition, under experienced guidance, leaving England June, to explore rivers Central Brazil, if possible ascertain fate Colonel Fawcett; abundance game, big and small; exceptional fishing; room two more guns; highest references expected and given.”

Fleming felt that the ad had “the right improbable ring to it.” Today, its clipped and credulous pomposity reads as an artifact of the golden age of dilettante exploration. Adventure travel, of course, has always been a romantic’s pursuit. Yet such romantics were unusually thick on the ground during the late nineteenth and early twentieth centuries. Weaned on the melodramatic novels of H. Rider Haggard, flush with the free time and money granted to those on the right side of the industrial age, these men trekked across the lesser-known continents, hoisting the standards of geography, and ethnology, and science, however loosely defined.

“Nowadays, being an explorer is a trade, which consists not, as one might think, in discovering hitherto unknown facts after years of study, but in covering a great many miles and assembling lantern-slides or motion pictures, preferably in colour, so as to fill a hall with an audience for several days in succession,” lamented the anthropologist Claude Lévi-Strauss, who would himself visit Mato Grosso a few years after Fleming. Such explorers did win significant fame, bestowed indiscriminately by a pre-mass-media public eager for exotica. Their travels were lauded—and often financed—by the press, which knew that danger porn sold newspapers. Their findings, most of the time, were of very little practical use.

Even so, these travelers were generally quite serious about their own ambitions, as if their efforts to map some irrelevant river put them in the same class as Pizarro or Cortés. The books that resulted from their South American travels were cut from the same dull cloth. In 1913, having failed to win the presidency as the candidate of the Bull Moose Party, an aged and remarkably ill-prepared Theodore Roosevelt set out on a Brazilian expedition. His book, Through the Brazilian Wilderness, explained how he had plumbed the darkest interior, inspired the government to spruce up the Rio da Dúvida with a new name (Rio Roosevelt), and faced down the deadly piranha: “The rabid, furious snaps drive the teeth through flesh and bone. The head with its short muzzle, staring malignant eyes, and gaping, cruelly armed jaws, is the embodiment of evil ferocity; and the actions of the fish exactly match its looks.” (“All one can say,” writes John Ure in Trespassers on the Amazon, “is that his companions did not begrudge him his final fling.”)

Roosevelt was preceded by the flamboyant writer and explorer Henry Savage Landor, who, according to David Grann, roamed the Brazilian interior “dressed as if he were heading off to a luncheon in Piccadilly Circus.” Landor’s own Across Unknown South America combines a bluff and imperious tone with the narrative verve of a shipping manifest. When not describing the scenery in slide-show fashion or endlessly marking the changes in elevation, the author complains of the country’s inadequate accommodations and the “contemptible imbeciles” with whom he was forced to travel. Landor’s men “mutinied and nearly shot him,” writes Grann; any of us would have done the same.

Justin Peters is editor-at-large of the Columbia Journalism Review.