They called it Cru Sauvage. The impeccable Swiss packaging alluded to its aboriginal provenance, and inside were two bars wrapped in golden foil, 68 percent cacao. I'd paid $13 (plus shipping!) for these skinny little planks of chocolate, just 100 grams' worth of "Wild Vintage." That's $60 a pound. After savaging its wrapper, I placed a square of the dusky stuff on my tongue and closed my eyes.

Bolivian Amazon chocolate

Volker Lehmann Volker in his element

Cacao Wild cacao

Chocolate is the one of the most complex foods we know. It contains more than 600 flavor compounds. (Red wine has only 200.) Chocolate can be bitter, sweet, fruity, nutty, and savory all at once. It takes the vast library of taste and blends it into one revelatory package. The tropical cacao tree has secret things to tell us about flavor and desire, and for more than a decade I've made a hobby of tracking down those secrets.

This incredibly rare and expensive chocolate was produced by the venerable firm of Felchlin, which claimed that it was unique in the world, made from an ancient strain of cacao native to the Bolivian Amazon—i.e., wild cacao, au naturel, unmolested by millennia of botanical tinkering. It hit me with an intense nuttiness, but without the slightest hint of bitterness, a combination I'd never experienced. Aromatics burst in my sinuses. Citrus and vanilla. The flavor dove into a deep, rich place, and then, just as I thought I had a handle on it, the bottom fell out and it dove some more. That might sound ridiculous, but I've spent an inordinate amount of time "researching" the best chocolate in the world, geeking out on it like the most obnoxious sommelier, and this was something entirely new.

When the feeling finally began to subside, I opened my eyes and started looking for the man responsible.

HIS NAME WAS Volker Lehmann, and he was the only reason Cru Sauvage existed. Before I'd even tasted the chocolate, I'd gleaned the basic elements of the story from the folks at Felchlin: Agronomist enters Bolivian rainforest and makes startling discovery. Volker was the visionary connoisseur on the ground, in the shit. Felchlin was just smart enough to recognize what he'd found. The company invested in specialized equipment, began production, and brought the first fruits of Volker's labor to the European gourmet market, in small quantities, in 2005. It was three years before I heard of it.

After my own chocolate enlightenment, I had to know more. It wasn't easy making contact with Volker, but once I did, he told me he was just scratching the surface. Demand greatly exceeded supply, and there was much, much more out there. He was planning a trip to Bolivia's Río Grande, a remote tributary of the Amazon that, it was said, held vast chocolatales, as the forests of wild cacao are called. There he would visit the Amazonian tribespeople who lived along the banks, offer them employment as cacao gatherers, and eventually, he hoped, set up jungle processing stations in their villages. Did I want to tag along?

Yeah, I was in.

Six frustrating months later, on the other side of a series of false starts, logistical snafus, tropical deluges, and cruel vaccinations, I finally met the bald, athletic 53-year-old in the jungle city of Santa Cruz, Bolivia. From there, we hopped on a 16-seater to Trinidad, a swampy town with frogs trilling in the crumbling gutters. It was early March, the tail end of the rainy season; the rivers had risen 30 feet and spilled across the forests. Trees stood in six feet of water. Piranhas had abandoned the river channels for better hunting in the woods.

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.

DANTE WAS OUR GUIDE—a very inauspicious name, it seemed. Volker and I climbed into his dugout, and he yanked its outboard to life, steering us between curtains of endless rainforest. Combate lay three hours downstream. It was classic Amazon: flocks of green parrots and blue-and-yellow macaws flying across two by two; pink river dolphins surfacing; the drumroll of cicadas running up and down the river. I began to feel really, really good. It could have been the jaw-dropping wildlife and the sweet, clean tropical air, but it was probably the big fat wad of coca leaves in my cheek.

The sacred plant of Bolivia, coca is chewed by most of the indigenous population, and Dante seemed to have an eternal quid of it in his maw, so I'd asked for a little. I stuffed the dried leaves inside my cheek, added a smear of baking soda to start the chemical reaction, and let the alkaloids slowly ooze into my bloodstream. First, my tongue and cheek went numb, then things began to occur to me. One was that there is no better way to float down the Amazon than on the wings of a mild coca high. Another was that it's a crying shame that cocaine, a superconcentration of the alkaloids, has screwed things up, because natural coca is one of the world's best drugs. It simply makes whatever you happen to be doing the most deeply satisfying thing in the world. Three hours on a hard wooden seat? Twenty-four hours without food? No problemo, señor.

Curled up in the bow of our boat with his rifle, scanning the banks for tasty monkeys, was Aurelio Rivero. Aurelio, who grew up on a remote homestead in the area, made his living as a cacao trader, plying the river system in his dugout, buying sacks of cacao from the indigenous families that lived along the river, piling them precariously in his canoe, and selling them down in Trinidad, where Volker met him in 2008.

By then, Volker was already buying wild cacao from several traders and trying to generate interest outside of Bolivia. But in recent years, word of the chocolatales' existence had leaked out, and they'd become something of a cause célèbre with conservation organizations, both international and local. "This cacao was lying in front of their eyes all of the time!" Volker told me. No one had ever thought it was worth much. "And then I put my own money behind it and did it. And then people started saying, 'He's taking our resources! Getting filthy rich!' "

In reality, his goal is the same as the conservationists': to preserve the chocolatales, which he thinks should be UNESCO World Heritage sites, and move ever closer to "long-term sustainability in every economic, social, and environmental aspect." But he believes in the market-driven approach: "These forests have no value except for cacao. If they have no value, they'll be cut down [i.e., landowners will sell the timber instead]. The more interest you have in cacao, the more you save the forest. The most sustainable thing we can do is to raise the interest." But a decade of groundwork in Bolivia had taught him to respect the bizarre intricacies of the Amazonian economy. "Many, many people have lost their fortunes in Latin America. There's no Bolivia for Dummies! You have to figure it out yourself."

And that, he thinks, is where the nonprofits have failed. "They make a deal with an indigenous group, get some nice photos, then run to the grant funds, overpaying for almost any type of cacao, no quality whatsoever," and then selling it domestically. Rather than conservationism's old "Buy the land, create a beautiful park" approach, this is the new school's "Help people and places function together healthily and indefinitely" tack.

"They kicked the ball out of my hand," said Volker. "Many people here look for a certain threshold of money, and then they stop harvesting. Once the beer is secure, there's no reason anymore. Westerners think that by giving more and more money incentive, people will do more. Actually, they do less. Leisure is very highly valued in this culture. They have no bills. They're not hooked into the system."

Alex Whitmore, co-founder of Taza Chocolate—a company that also does business in Bolivia and is considered the paragon of direct, supportive relationships with Third World cacao farmers—agrees: "If they get free money, they don't want to work. Nonprofits pumping money into a community stymies the growth of sustainable agriculture. There's a balance that needs to be struck between nonprofit aid and for-profit industry. It's pretty messed up because of the coca."

As in cocaine. A strange cacao–coca co­dependency exists in Bolivia. "You get all this assistance and money to develop other opportunities for locals if, and only if, you have lots of coca production," said Whitmore. "They plant coca so they can get money to stop planting coca. That's USAID, U.S. government aid." It's a beautiful sell: Help transition the poor Bolivian farmers from coca to cacao, from the evil alkaloid to the acceptable one. "These aid programs basically exist to support the salaries of those who work for them, not necessarily to provide the communities with sustainable growth."

While Volker battles the nonprofits on one flank, he must contend with domestic chocolate makers on the other. One competitor even filed a complaint with the Ministry of Agriculture, claiming that Volker was robbing Bolivia of its natural wealth (as was done with rubber trees a century ago).

"They're just protecting their business," Whitmore opined. "They're trying to grow very aggressively, and they don't want anyone else doing cacao in Bolivia. He's not just buying and exporting; he's actually trying to organize the farmers. They would see that as a direct, competitive threat."

So Volker was going where no sane capitalist had gone before. He had to reach the cacao first. He also hoped to improve the quality. Only 20 to 40 percent of the cacao in Trinidad is good enough to be used in Cru Sauvage. The rest is rotten, moldy, or poorly fermented. Volker painstakingly picks the good beans from the bad and leaves the rest for the domestic Bolivian market, which is not picky. The problem is that the tribes, who don't eat chocolate themselves, have neither the knowledge nor the equipment to ferment and dry premium beans. Volker hoped to change that by setting up buying stations along the rivers and raising the level of coordination. "My role is to bring order to the jungle," he said.

If anywhere needed his services, it was the Río Grande. Thousands of acres of chocolatales lining the river. Some of the last known wild cacao on earth, much of it going unharvested or rotting before it got to market. Or so Aurelio claimed. "Show me," said Volker.

IT DIDN'T TAKE LONG. At a bend in the river, Aurelio gestured. I peered into the gloom. The understory was filled with yellow pods the size and shape of Nerf footballs hanging directly from tree trunks. A sheet of river was bleeding into the forest. Volker broke off a pod and stared at it intensely.

"Very impressive," he muttered to himself. "I've already learned something new: Cacao can be very productive in understory riverbanks." Earlier, I'd told Volker that people I knew considered wild cacao a myth, and now he turned to me. "No wild cacao? Bring them here! Show them this!" He laughed, smacked the side of the pod against the edge of the canoe, and twisted it open. Inside were dozens of maggoty-looking things. He held it out for me. I stuck a handful of the white seeds in my mouth and sucked. A sweet, lemony, delicious pulp came off. This, of course, was what had attracted people and monkeys to cacao for thousands of years before some hungry and desperate soul decided to see what would happen if you roasted the dried seeds.

I sucked seeds all the way to Combate, one of a scant few settlements on the Río Grande. With a population of perhaps 80 people, Combate represented the largest cluster of potential labor on the river. It was key to Volker's vision. For two years he'd been laying the groundwork through people like Aurelio. And now it was time to make his pitch.

A dozen thatch-roofed palapas came into view. The entire settlement was underwater, the palapas on posts. Toddlers waded through the current. Chickens perched on carts, stumps, or any other dry thing they could find. The settlement was full of mango, guava, banana, and cacao trees and weird pets: wild piglets, macaws, coatis.

We pulled up on the flooded bank next to a larger wooden boat festooned with children, who were soon clustered around us. The large boat belonged to Francisco Brito, a spokesperson for the Yuracare tribe, who lived farther upriver. Francisco also traded in cacao. He was here to meet Volker and set up a deal for the upper Río Grande. Francisco had brought 20 cases of Colônia, a cheap Brazilian brew smuggled across the border. Bolivia and Brazil meet along some 2,000 miles of navigable rivers and uninhabited mush, and across that border flows all manner of goods. Cocaine goes east; pirated CDs, stolen Chinese motorbikes, and beer come west.

Beer is the Dom Pérignon of the Amazon. At about 80 cents a can, it's a sign of conspicuous consumption. In the lowlands, the surest way to get everyone's attention is to show up with an obscene amount. We had everyone's attention.

At least, we would have if we'd turned up a few hours earlier. Francisco had already spread the wealth, and the men of Combate were now drooping from his boat like tree sloths. A small, handsome man in his thirties with bloodshot eyes, spade-shaped earlobes, and a sailor's gait roused, stumbled over, and identified himself as Guillermo Figueroa, spokesman for Combate. "You're too late," he said, weaving. "Today we're drinking. Tomorrow we'll meet." Then he grabbed a fresh case and splashed off with his buddies.

There was nothing to be done but crack a few ourselves. Somebody handed me a beer and a bowl of fried piranha, and a crew of locals grabbed our hammocks and packs to set us up for the night in a simple pavilion in the middle of the settlement, their church. When I tried to hang my own hammock, it seemed to upset everybody.

"People here relate differently," Volker explained. "It's still the old patron system. They respect hierarchy. They want me to order them." Ultimately, that was why we were here. "They want to see the boss, to see if it's real. Who calls the shots? Who has the cash? That very minute, things really start. But if you become the boss, you have responsibility. They come to you and say, 'Look, I need this, and I need that.' Or something happens. Somebody gets hurt and has to be flown out. Then I hire a plane and get that guy out and take him to a hospital. There's no discussion. I can't say, 'Oh, no, that costs too much. I can't do it.' Then I've lost. It's tricky, but it's quite a straightforward system if you know it."

If Volker could sometimes sound alarmingly German, this no-bullshit approach was refreshing, and you had to respect his experience. Anachronistic, decidely "insensitive" order in place? Roll with it. This is business.

Beer cans and cacao pods floated past, and Volker lit a cigarette. As the darkness and mosquitoes began to ooze in, the sky turned all mango and papaya.

"Kitsch," he said.

LOOKING SURPRISINGLY chipper, Guillermo turned up in the morning and began whanging on an old piece of outboard with a length of pipe. If this was the church, then that, we supposed, was the bell. There was instant coffee, fried plantain, and more piranha. Guillermo popped open a Colônia and waited.

An hour later, the only people assembled were Volker and me. Guillermo pounded on the metal again in frustration. Grudgingly, the rest of Combate joined us. Guillermo and Volker made small talk in Spanish as the others gathered. Why was the village called Combate? No one could remember, Guillermo said. Some trouble with another tribe.

I was the first person Guillermo had met from the States. He was stunned to learn that coca was illegal there. Volker asked Guillermo if any of the children were his.

"Actually, I have 21 children," he replied.

"Wow, the Church must have told you to go forth and multiply," Volker said.

"No, they tell us we should have only two or three."

"Then what happened?"

"I have no television," said Guillermo with a sly smile. The crowd laughed, and Guillermo basked in the attention. He was wearing a green soccer shirt and jean shorts and his fly was open. Volker turned to me and said, in English, "There's always one like him. He has no actual power. He doesn't make decisions. There are some quiet ones observing, possibly women, who really decide. We have to get closer to the women. Because they care for the children, they tend to be more sensible."

Then Volker made his case. The cacao that the people of Combate collect, he told them, is some of the finest in the world. But it's worth lots of money to the rest of the world only if it's perfectly fermented and dried. And right now, it isn't. Just look around.

The village was littered with comical attempts to dry beans in an inundated rain­forest. Cacao was heaped anywhere that promised to stay clear of the rising waters—canoes, huts, bags hanging from mango trees. None of it was getting terribly dry, and some of it was starting to germinate.

"If you work with me," Volker proposed, "I'll build a station where you can bring the cacao. I'll have people—local people like Aurelio—to take care of it. I'll pay you immediately. I'll even bring you gasoline in advance, so you can use your outboards to get to the cacao. I'll have a nice boat to carry the cacao downriver." He smiled at Guillermo. "Maybe I'll even build you a brewery."

The crowd laughed again. Guillermo put his hand to his mouth in a shoveling motion. "What about food? I need to feed my people. Why don't you pay us now for next year's cacao crop, so we can get the things we need?"

Volker shook his head. He would pay a premium for good cacao, but he would not pay in advance, and he would not overpay. (Cash in advance disappeared in a spree of beer and Speed Racer T-shirts. "If you increase the price for no reason," he had explained to me earlier, "then the quality actually goes down, because they think you're stupid.")

The people of Combate didn't think Volker was stupid. They said, Sure, set up your buying station, upgrade our boats, take the drying off of our hands. The meeting adjourned and Volker broke out some paper and crayons and held a cacao-drawing contest for the kids, who looked as though they'd never seen a crayon.

A woman watching the kids approached us. "Next time you come," she said, "please don't bring any beer."

VOLKER GREW UP outside of Berlin, near the coal mines where his father put in double shifts six days a week. After getting a degree in tropical agriculture (on his dad's day off, they gardened together), he began working for the German Volunteer Service in the Dominican Republic. This was the 1980s. Volker planted cacao and other tree farms and was later put in charge of a rabbit-breeding program, which didn't go so well. Locals refused to eat the varmints: "They're too close to rats. Same long teeth." The program ended with Volker throwing a party for his friends and grilling 80 rabbits.

The GVS moved him to Bolivia in 1991, where he entered the jungle with a Chimane Indian guide and first discovered the wild cacao. He then returned to Germany to work in Frankfurt for a number of years. When he came back to Bolivia in 2000, he was amazed to find that no organization had yet begun developing the cacao. In the Amazon, he consulted for a number of Fair Trade groups, evaluating the sustainable-harvest potential of everything from rubber trees and Brazil nuts to palm oil and a red tree latex known as dragon's blood. But the wild cacao captivated him. As he tasted more of the beans, he became the first person to identify a staggering disconnect: Bolivia had a vast supply of some of the best cacao on earth, and no one knew it.

Convincing the gourmet chocolate industry, however, was another story. ("Nobody even knows that Bolivia has cacao," he told me. "They think we grow llamas.") Part of the problem was that the wild beans were only half the size of cultivated beans and couldn't be processed with standard equipment.

"I was running around with these small beans for two years. Nobody wanted them. I sent them to Scharffen Berger. I sent them to Japan. No good, no good, no good. Everyone. It was a very uncertain situation. I started investing more effort, time, money, everything, with no promise that it would work out. I was just convinced that the cacao was wonderful."

He learned of some land for sale that included hundreds of acres of cacao forest. He borrowed money from his father-in-law and paid $13,000 for the 1,500-acre property in 2003. With the success of Fair Trade coffee spilling over into cacao, and with makers of ultra-high-end chocolate suddenly warring over access to the finest beans, he figured it was only a matter of time. Eventually, hundred-year-old chocolatier Felchlin took notice and—as only a small-scale, high-end maker would—adapted some antique equipment to Volker's unusual beans. Then they summoned him to Switzerland. "They brought me into a conference room," said Volker. "All these serious faces sitting around a table. Very Swiss. There were five chocolate samples on the table. They said, 'Pick out the one made with your cacao.' I tasted all five. I said, 'That one.' They said, 'You're right, and we love it.' "

WE BOUGHT ALL THE CACAO worth buying in Combate. It would travel by boat with us down to Trinidad, then by truck, over the carnage known in Bolivia as the road system, more than 900 miles to Volker's warehouse in La Paz. At an altitude of 13,000 feet, La Paz is the highest major city in the world. Visitors regularly conk out, their brains sputtering in the low oxygen. The cool Andean air makes it the perfect place to store cacao year-round without air conditioning. Volker uses a defunct racquetball facility, 100-pound sacks of dried cacao piled high on lovely wooden floors.

From La Paz, the cacao is trucked over a 15,700-foot pass and then hurtles down the Pacific slopes to the Chilean port of Arica, where a feeder ship carries it to Panama. There, it gets loaded onto a large container ship for the trip through the canal and across the Atlantic to Rotterdam, where it gets transferred to another feeder ship and brought up the Rhine to Felchlin's warehouse in Basel, Switzerland. "I think the price of Cru Sauvage is very cheap for what we all do," said Volker.

We left Combate at dawn, carving chunks out of a local sausage and washing it down with beer. "German breakfast," Volker said approvingly. I nibbled on some raw cacao beans. There was a hint of greatness in them, but they were a long, long way from being chocolate. We had switched to a larger wooden boat, which included a trellis roof with a blue tarp to block the punishing sun. The tarp didn't reach the back of the boat, so Dante had thrown a salted pig carcass—our meat for the next two days—over the top for shade. We had no radio or backup, and the outboard had no casing and a number of jury-rigged parts. I was impressed with everyone's confidence in its ability to deliver us through three days of wilderness.

Between the bags of cacao, the backpacks, the hammocks, the piranha carcasses no one had cleaned up, the beer cooler, and the bottles of water and gasoline, the only place to sit was on the narrow gunwales—torture no amount of coca could disguise. Our goal was to visit several cacao-gathering homesteads, as well as the settlements of Palermo and Jerusalem, Aurelio's childhood home. "First Palermo, then Jerusalem," Volker muttered. "Sounds like a crusade." Cacao was everywhere. We found an old, shirtless man with a skin disease devouring the right side of his body. He sat in a hut surrounded by well-manicured cacao trees. His name was Pedro, the last of a community of Trinitario Indians, and he'd lived there for 45 years. Pedro said there were 2,500 acres of chocolatales in the area, but there was no one left to harvest them. I couldn't believe it. In other parts of the world, chocolate companies fight like hell over the paltry supply of high-grade cacao varieties. People have even been shot in Venezuela. Here, it rotted in the forest.

"What if I helped you get pickers here during the season?" Volker asked. "And I provided food, training, and boats? And you ran the show? And we paid you a premium for everything you harvest?" "Why not?" said Pedro. They shook on it.

Palermo, we soon discovered, had been abandoned to the floods. After 12 more back-breaking hours, we reached Jerusalem, still a foot or so above the floodwaters. Aurelio and his brothers had inherited a shack surrounded by 7,500 acres of swampy rainforest rich in cacao. The family had been hard at work: Every square inch of ground we could see was covered in a thick carpet of empty, composting cacao pods. I was thrilled to be off the boat, but as we walked toward the shack over the crunching pods I suddenly noticed that they seemed to be rippling. The entire grounds, even the floors of the shack, were alive. The ants had moved in.

By this time, I had a relationship with the jungle like that of a beaten dog to its master: I loved it, but it just kept hurting me. I'd worried about all the wrong critters. It wasn't the jaguars; never saw one. It wasn't the caiman; those we ate ceviche style, raw tail meat sliced thin and marinated in fresh lemon juice. Ditto for the piranhas and snakes. (You don't even want to know about the countless tiny vertebrae.) I even got along famously with the tarantulas, which have a personality not unlike the Dude of The Big Lebowski.

But the fucking ants. Mosquitoes, ticks, chiggers, and gnats? Awful. But the ants, streaming through the forest in black rivulets of sadism, are the real lords of the jungle. There is far more ant biomass than human in Amazonia. They attacked from the ground, came boiling out of old canoes, fell from trees. Staying in Jerusalem was suicide. Dante, who'd absorbed enough coca alkaloids to keep the city of Medellín partying for a week, voted for motoring blindly through the night. Overruled. "I know a place," said Aurelio.

We puttered down an old, dead-end arm of the river as it turned purple, mirroring the sky. Carpets of green dragonflies seeped over the water as river dolphins surfaced and fireflies winked in the trees to the rhythm of the frogs. At the end of a lagoon, a single hut rose out of the water on stilts. As we approached, a gnarled old couple tottered out. If they were startled by the sudden turn their evening was taking, they didn't show it.

I HAD HIGH HOPES of making it back to Trinidad the next day—Volker had promised me the best steak of my life when we arrived, and even a skanky hotel room with cold running water was starting to sound like purest hedonism—but the outboard gave up the ghost midmorning. Dante and Aurelio proceeded to do the desperate and hopeless things with screwdrivers that men always do in such situations.

With the engine dead, the sounds of the jungle rushed in. One has this idea of the rainforest ringing with dulcet birdcalls, but for whatever reason, most birds in the Amazon sound as if they have hairballs. The parrots screech. The macaws hack. The hoatzin, an evolutionary throwback, looks and sounds like Billy Idol. Walking the rainforest is like making the rounds in a tuberculosis ward.

They worked on the engine for hours. Black cumulonimbus anvils approached from the west. I watched lightning flick between them as howler monkeys tried to outroar each other. I wondered how long we could all live on the bags of raw cacao beans in the boat. I wondered how it was possible that I'd been on the world's greatest cacao river for days without tasting a single piece of local chocolate.

Our aluminum cooking pot was sacrificed. It took two hours to hacksaw a piece of metal out of it and bend it into the needed shape. It was an impressive display of Latin MacGyverism, and for a moment after Dante fired up the motor, my heart flushed with hope. Then the aluminum disintegrated like taffy.

This time Dante just yanked up the outboard, threw it on deck, and stared as we drifted. Then he reached for his coca pouch. Rain came sizzling up the river and lashed my face. Thunder rumbled in the distance, and the roaring on the banks closed in, as if the jungle itself were screaming in anticipation.

The river led to Aurelio's brother Angel's store, in the village of Camiaco, less than two miles from where we'd broken down. We managed to limp downriver and arrive at cocktail hour. I considered asking why, if they knew Angel's place was just downstream, they'd felt it necessary to spend five hours, by God, engaged in ad-lib engineering, but the Marlow part of my brain whispered, "Don't—that line of questioning leads to madness."

Instead, we talked cacao with Angel. He bought from all the collectors in the area. "I can get you ten tons a year," he told Volker. I timidly asked if he might have a little stash of homemade chocolate around. Angel disappeared into his store and soon emerged with a two-pound lump of fruity, fragrant magic. Its otherworldly aroma hit me from 20 feet away. After all the miles, the bugs, the rancid pork, I grabbed it and held it close to my face, whimpering like Gollum with his ring.

"The volume of cacao from this river—" said Volker, looking giddy, "it's much better than I thought. If I can take out 60 percent, I'm good."

The next day, after some radio calls and Escher-esque logistics, we found ourselves back in Trinidad, where Volker made good on the steak. Trinidad is surrounded by millions of acres of marshy grasslands filled with white zebu cattle. At restaurants on the main square, seven dollars gets you a free-range, grass-fed slab that would make Fred Flintstone weep. Volker and I were carving into two, watching the people of Trinidad sweep by on Haojin 150s, sometimes two, three, even four people to a bike, when his assistant walked up. There was good news. Indians from an entirely different river system (I promised not to reveal which one) had turned up in town, desperate to sell their cacao. They had hundreds of miles of chocolatales, they said, and there were no buyers. Might Mistah Volker be interested?

Volker grinned, finished his steak, and lit a cigarette. Business was good. Felchlin was fielding inquiries about new partnerships and recipes. The local market was completely sated on subpar beans. The nonprofits were off chasing funding. A virgin river in Amazonia was ripe with yet more cacao, and the only person in the whole wide world in a position to pluck it was Volker Lehmann. "Find another boat," he said. "Go upriver. Buy cacao, buy cacao, buy cacao." "You must eat a ton of chocolate," I said wistfully.

"I don't have a taste for it," said Volker, dry as a stone. "I like Gummi Bears."