Morde declined to reveal the location of the city, for fear of looting. It seems he kept this information even from Heye himself.

In another account, written for a magazine, Morde described the ruins in detail: “The City of the Monkey God was walled,” he wrote. “We found some of those walls upon which the green magic of the jungle had worked small damages and which had resisted the flood of vegetation. We traced one wall until it vanished under mounds that have all the evidence of once being great buildings. There are, indeed, still buildings beneath the age-old shroudings.

“It was the ideal spot,” he continued. “The towering mountains provided the perfect backdrop. Nearby, a rushing waterfall, beautiful as a sequined evening gown, spilled down into the green valley of ruins. Birds themselves, as brilliant as jewels, flitted from tree to tree, and little monkey faces peered inquisitively at us from the surrounding screen of dense foliage.”

He questioned the older Indians closely, learning much about the city, “handed down to them by their ancestors who had seen it.”

“We would uncover, they said, a long staired approach to it which would be built and paved after the manner of the ruined Mayan cities to the north. Stone effigies of monkeys would line this approach.

“The heart of the Temple was a high stone dais on which was the statue of the Monkey God himself. Before it was the place of sacrifice.”

Morde brought back a number of artifacts—figures of monkeys in stone and clay, his canoe, pots, and stone tools. Many of these are still in the collections of the Smithsonian. He vowed that he would return the following year “to commence excavation.”

But World War II intervened. Morde went on to become an OSS spy and war correspondent, and his obituary alleges he was involved in a plot to kill Hitler. He never returned to Honduras. In 1954, Morde—sunken into alcoholism, his marriage failing—hanged himself in a shower stall at his parents’ summer house in Dartmouth, Massachusetts. He never did reveal the location of the lost city.

Morde’s account of finding the Lost City of the Monkey God received wide press and fired the imagination of both Americans and Hondurans. Since his death, the location of his city has been the subject of intense speculation and debate. Dozens have searched for it without success, parsing his writings and accounts for possible clues. One object became the Holy Grail of searchers: Morde’s beloved walking stick, still in the possession of his family. Carved into the stick are four enigmatic columns of numbers that seem to be directions or coordinates—for example, “NE 300; E 100; N 250; SE 300.” A Canadian cartographer named Derek Parent became obsessed with the markings on the stick and spent years exploring and mapping Mosquitia, trying to use them as directions to the lost city. In the process, Parent created some of the most detailed and accurate maps of Mosquitia ever made.

The most recent search for Morde’s lost city took place in 2009. A Pulitzer Prize–winning journalist for the Wall Street Journal, Christopher S. Stewart, undertook an arduous journey into the heart of Mosquitia in an attempt to retrace Morde’s route. Stewart was accompanied by archaeologist Christopher Begley, who had written his PhD dissertation on Mosquitia’s archaeological sites and had visited over a hundred of them. Begley and Stewart went upriver and made their way through the jungle to a large ruin called Lancetillal, in the upper reaches of the Río Plátano, which had been built by the same ancient people Strong and other archaeologists had identified as once occupying Mosquitia. This previously known city, which had been cleared and mapped by Peace Corps volunteers in 1988, was in the approximate area Morde claimed to be, at least as far as Begley and Stewart could ascertain. It consisted of twenty-one earthen mounds defining four plazas and a possible Mesoamerican ball court. In the jungle some distance behind the ruin, they discovered a white cliff, which Stewart believed might have been mistaken for a broken wall from a distance. He published a well-received book about his search, called Jungleland: A Mysterious Lost City, a WWII Spy, and a True Story of Deadly Adventure. It is a fascinating read, yet despite Begley and Stewart’s best efforts, there simply wasn’t enough evidence to settle the question of whether the Lancetillal ruins were indeed Morde’s Lost City of the Monkey God.

As it turns out, all these researchers have spent almost three-quarters of a century looking for answers in the wrong place. Morde and Brown’s journals have been preserved and passed down in Morde’s family. While the artifacts were deposited with the Museum of the American Indian, the journals were not; this in itself is a remarkable departure from standard practice, because such journals normally contain vital scientific information and belong to the financing institution, not the explorer. The keeper of the journals until recently was Theodore’s nephew, David Morde. I was able to get copies of the journals, which the Morde family had loaned to the National Geographic Society for a few months in 2016. Nobody at National Geographic had read them, but a staff archaeologist kindly scanned them for me because I was writing a story for the magazine. I knew that Christopher Stewart had seen at least parts of them but had been disappointed to find no clues as to the location of the Lost City of the Monkey God. He had assumed that Morde, for reasons of security, had withheld that information even from his journals. So when I began flipping through them, I didn’t expect to find much worthy of note.

There are three journals: Two are hardcover books with dirty canvas covers stamped “Third Honduran Expedition,” and a third is a smaller spiral book with a black cover labeled “Field Notebook.” They run to over three hundred handwritten pages and give a comprehensive account of the expedition from start to finish. No dates or pages are missing; every single day was recorded in detail. The journals were the combined work of Brown and Morde, who each made their own entries in the same books as they journeyed into the heart of darkness. Brown’s easy-to-read, rounded handwriting alternates with Morde’s spiky, forward-slanted style.