To get within a reasonable distance of the indigenous settlement of Combate, a purported cacao hot spot on the Río Grande, we opted for a one-hour, $400 bush-plane ride instead of a four-day boat trip. Every landing strip along the river was underwater except one near an abandoned hunting lodge. As we approached, our pilot, a squat, mustachioed Bolivian of few words, pointed and shook his head in sad disgust. It was unsettlingly overgrown. Down on the river, two men in a dugout canoe waited. We swooped down for an inspection and—good God, he was landing in that stuff! Death smirked at me: All for a goddamned chocolate bar. But we punched into the brush and came to an amazingly soft stop.

I gave our (sad, disgusted) pilot two happy thumbs-up, hopped out, and landed on the home of some warlike ant tribe, which opened up a can of whup-ass on my sandaled foot. As he stood watching me do the first of many ant dances, Volker smiled thinly and said in Teutonic tones, "Welcome to the Amazon. If you stay, we eat you."

WILD CACAO? A MYTH, disappeared ages ago, extinct—that's what my industry sources had said, anyway. Chocolate is made by fermenting, drying, roasting, and grinding the almond-size fruit seeds of Theobroma cacao, which has been farmed—and therefore much changed by humans—for thousands of years. The ancestors of the Maya perfected the process in Mesoamerica, and it was later passed on to the Aztecs. In the 16th century, conquistador chronicles tell us, the Maya were cultivating vast cacao orchards throughout the Yucatán and Chiapas. It was thoroughly domesticated. Until recent genetic testing proved that the tree is actually native to Amazonia, many scholars believed it hailed from the Maya homelands.

Cacao was used as both drink and currency by the Maya: Ten beans got you a rabbit or a prostitute. When Hernán Cortés entered the Aztec capital of Tenochtitlán, in 1519, he found nearly a million cacao beans in Montezuma's coffers. Liquid chocolate played the role of blood in some Aztec rituals involving human sacrifice. The cacao pod seems to have reminded the priests of the heart.

The Spanish didn't quite get chocolate until they learned to mix it with sugar, and by the 17th century, Europe was cuckoo for cacao. The groves of Central America and southern Mexico couldn't keep up. Enter Brazil, where an inferior variety was being farmed. Though this cacao was higher-yielding and more disease resistant, it was also bitter as hell, so they cut it with lots of sugar. Europeans never knew the difference. Neither do you. The finer-flavored domesticated cacao of the Maya was long ago abandoned, so crappy Brazilian cacao—farmed primarily in Africa these days—is all most of us have ever known.

Ninety-five percent of chocolate is made with "bulk beans," meaning they taste like shit. If you think dark chocolate is bitter and nasty, blame the bulk beans. The tiny supply of good domesticated stuff—from makers like Valrhona, Scharffen Berger, and Amano—comes from old cultivars, grown mostly in remote corners of the Americas on farms that were never able to afford the switch to modern, high-yield varieties.

All of this I knew from researching gourmet chocolate for my book American Terroir. Then I stumbled upon the Cru Sauvage. Its wild cacao had always been harvested like any other fruit by the indigenous tribes, but it had never been shipped out of the country before, just hauled to Trinidad by middlemen, in poor condition, and sold on the domestic market. While working in the Bolivian Amazon as a consultant in 1991, Volker filed a report on the great potential he saw in the wild cacao. It was roundly ignored. He would later leave the idiots to their bureaucracy and pursue his vision alone.

Uh-huh, I thought, I've heard this story before, courtesy of Joseph Conrad: German guy hops on a boat, heads deep into the jungle, and then sends some freaky communiques before going rogue. Well, if Volker was Kurtz, I figured I was Marlow, fated to tell his story.