“Please, you must start from the beginning.” Parada had let his pipe go out.
“Okay, where the River of Ruin meets the Rio Tuira was a shallow falls that prevented idle boatmen from paddling up the tributary to this mountain. Gary discovered that the falls weren’t natural. It was actually a dam constructed of dressed stone that flooded part of the valley and raised the level of the River of Ruin by about ten feet. During the time of the Spanish rule, the only way to move around the jungle was to stay on the navigable rivers. By building a dam like they did, the Incas made sure the conquistadors wouldn’t pay much attention to the little river.
“Gary was sure this trick meant the treasure was buried somewhere below us on the river. He never considered that the Incas, master builders that they were, took their plan one step further. When they discovered this area, they were confronted by a ringlike mountaintop partially filled with water. But a cleft in one side prevented it from filling completely. By my calculations, that fissure was about forty feet wide at the top and nearly fifty feet tall.”
Despite his desire to hear the rest of the story, Professor Parada interrupted. “How did you calculate this?”
“The angle of repose,” Mercer answered. “The downward slope all around this mountain is a constant thirty-four degrees. Same with the valley flanking the River of Ruin. That is the natural angle that these soils settled into after a few million years of erosion. But the waterfall, at least the top fifty feet, is at a much steeper angle, nearly seventy-three degrees if taken in its entirety.”
“How’d you figure that?” Lauren asked.
“Basic trigonometry. It seemed unlikely that when this volcano grew over the course of countless eruptions that a plug of harder, and thus not easily eroded rock, could be perched like that on top of the gentler lower slopes. It had to be man-made.”
“A dam like the one down below,” Roddy exclaimed.
“Only much bigger.”
“So the Incas who raided the gold caravans built these dams to hide their treasure someplace inside this caldera.”
Mercer gave Lauren’s hand a squeeze. “Exactly. Once they’d stored away the gold, they sealed the fissure with their dam and let the lake fill up. No way anyone without modern diving equipment could find it.”
“Once the lake was filled, how would they hide the additional loads of treasure they stole?”
“I’m guessing that at the end of the dry season, when the lake level was already low, they would risk pulling a keystone from the dam to discharge enough water for them to cache it.”
Parada seemed satisfied with the answer to his question. “Once the keystone was replaced and the rains started, their hiding place would be hidden again.”
“And since rain in this country pisses down more regularly than I do,” Harry quipped, “I’d guess the lake filled quickly.”
“So where is it?” Roddy sounded like he’d already caught gold fever.
“The clue came from the journal I bought in Paris.” Mercer retrieved it from the waterproof bag under his chair. “Godin de Lepinay spent several months in Panama as a scout for the French canal effort. One of the things he wrote about was a volcanic lake in the north. It was the dry season and he was fascinated by the warren of caves in the island located in the lake’s center. He’d never seen anything like it. I think our island is also riddled with caves and that’s where the Incas hid their treasure.”
As one, all heads turned to the small island a quarter mile from shore, the spot where Mercer, Lauren and Miguel had spent the night surrounded by suffocating carbon dioxide. “We were camped on top of it,” she breathed.
“What do we do now?” Parada asked through a cloud of aromatic smoke.
“We blow up the dam, let the lake drain down to its natural level, and see if I’m right.” Mercer looked at the faces around him and had never seen such eagerness. “Lieutenant Foch’s men have already planted the explosives and we’ve got authorization from the government to drain the lake. They’ve alerted everyone living downstream on the Rio Tuira to expect a bit of a flood this afternoon.”
“By God, sir,” Parade said, slapping his leg as he too caught the fever, “what are we waiting for?”
“Well, permission from you to blow up a dam built by the Incas. I was afraid you might consider it an important artifact.”
Parada thought about it for a moment and conferred in Spanish with his companions. “Had you come to us a week ago I would have said no. But with the canal out of commission and little money to repair it other than what we can borrow from your country, Panama is going to starve. I think the loss of scientific knowledge is worth the benefits.”
“I know that wasn’t easy.” Mercer tossed him a sealed plastic sandwich bag loaded with 35mm film canisters. “Those are all shots of the dam. I also took about an hour of digital video when we planted the charges. That might ease your conscience a bit.”
Parada nodded. “
Sí, gracias
.”
They found a vantage spot several hundred yards from the waterfall that allowed them to see the bottom of the dam as well as part of the river valley. No one argued when Mercer handed the radio detonator to Miguel. The boy was solemn when he took it, sensing that it would forever wipe away the spot where his parents were killed. Miguel looked to Roddy for guidance. The Panamanian dropped to a knee and held Miguel’s trembling hands in his and together they pressed the button.
The explosion was muffled by distance and the way the charges had been pressed into fissures in the rock. A gout of dust and rock shards blew from the face of the dam and water glinted like diamond chips as it flew away from the detonation. The blast wave shocked hundreds of birds into flight and caused a riot of shrieking animals as it boomed down the valley. With the rolling thunder dying away, the party could hear the earth groaning as tremendous weights shifted inside the stone façade.
And then they noticed that there was more water flowing at the base of the falls than was going over its top. It was negligible at first but grew steadily until water gushed from the hole cleared by the explosives. As they watched, the force of water expanded the gap by clawing away more loose boulders. And by increasing the hole, more water was allowed through, which eroded more of the stonework. A large section of the dam cracked, geysers of water spouting from around its edges, and then it collapsed completely, sweeping away tons more material.
The carefully placed stones next to the rushing torrent were sucked into the maelstrom and swept down the valley. The banks of the River of Ruin were overwhelmed. Everything that once lined it was caught in the flood and uprooted. Trees were smashed down and stands of jungle were ripped away by the unrelenting flood. More of the dam broke away, huge crashes of stone and water that shook the earth.
Like stormwater flowing through a drain, the water gushed through the opening, allowed to follow its natural course for the first time in hundreds of years. It was mesmerizing to watch, the force of that much water released all at once, and the party stood rooted for nearly an hour just to absorb it.
The deluge drew down the level of the lake much faster than Mercer had predicted. He’d used the Manning hydrology formula to determine that the billion-plus cubic feet of water in the lake would need about eight hours to drain away, but it appeared his resistance figures were off. Water flow was greater than the fifty thousand cubic feet per second he’d estimated.
He shot a furtive glance back at the little island in the center of the vanishing lake. As the level dropped and the shore of the lake seemed to retreat, more of the island was exposed. Already the spot where he had hidden Gary’s boat that fateful night was ten feet from the water’s edge.
“There’s no sense standing here,” he said at last. “Why don’t we take the boats out to the island to wait.”
They headed back. Where once the lake lapped just feet from the camp, they were confronted by an expanse of mud flats that dropped sharply to the retreating water. Much of it was so unstable that sheets of it oozed downward. The pier looked oddly out of place sitting alone on its pontoon barrels high above the shoreline. The three boats had drifted at the end of their tethers as the current tried to suck them down the ruined dam. Had Foch not lengthened the painters, the little craft would have been high and dry by now.
He and Rabidoux drew the boats back toward the shore and helped the party into them. Carmen had no interest in joining them so she remained behind with her children, although nothing could keep Miguel from the adventure. They motored out and circled the island once looking for evidence of a cave. That they didn’t see anything didn’t dampen their expectant mood.
The boats were beached and everyone was forced to wade through the clinging mud to reach high ground. Harry had the worst of it because of his fake leg and needed Foch and Mercer to help him. More beers and a Coke for Miguel were dispensed from the cooler they’d brought. Roddy also passed out sandwiches that Carmen had made for the occasion.
The conversation drifted from a recount of what had happened to the canal for the benefit of Parada and his companions to the possibility of finding the legendary treasure. Every half hour or so one of the group would excuse themselves and walk around the island, keeping clear of the mud by stepping along its old shoreline. As the sun sank toward the horizon, Mercer announced he would make one last circuit and that afterward they should head back to the camp to wait out the night and return in the morning. Lauren got to her feet as Mercer set off.
“Mind some company?” She grinned, taking his hand.
“Not one bit.”
They got no more than a minute from camp when Mercer stopped suddenly. Lauren turned to him, tilting her head, expecting to be kissed. She opened her eyes after a second, piqued that Mercer hadn’t gone through with it. He wasn’t even looking at her. His attention was riveted to a strange rock formation slowly emerging as the water receded. “What is it?”
“Pay dirt.”
“A cave?”
“I think so. It might take another hour to be sure. The water’s still hiding a lot of it.”
Even before they could return to tell the others, Professor Parada and Roddy had come out to see what was taking so long. A minute later they all made their way down the muddy shore. The morass was thick and stunk of rot.
They had to circle around the projection of rock that hid the cave and wade through water up to their knees to reach the entrance. The cavern was roughly thirty feet wide and about six tall, a black mouth that led into the earth. The rocks were cool and slick. Mercer was the only one to remember a flashlight.
Holding it in front of him, he stepped into the entrance, feeling along the stone floor with his feet to make sure it didn’t drop away suddenly. Water dripped from the ceiling like rain. Lauren joined him, keeping behind him to step where he stepped.
The floor vanished. Mercer probed out with his foot, feeling underwater, and found a step six inches down. He found another and another. He was on a staircase that disappeared into the murky water. He stopped when he was chest-deep.
“We might need diving gear after all,” Lauren remarked.
“No, the water’s dropping. I think there’s a subterranean outlet below us that will drain the cave. We just need to give it a little more time.”
In just a minute the water was down to his waist again and Mercer took another couple of steps. Lauren stayed a few stairs above him, shivering in the cold water. When he could, Mercer took another step.
“I think I reached the floor.” He turned to look back. The cave’s entrance, forty feet behind them, was ten feet over their heads. The others were silhouetted against the dim light filtering down the passage.
Somewhere in the darkness he heard water rushing through a small side passage, draining away as he’d predicted. The cavern was larger than the beam of his small light could reach. Mercer and Lauren moved to the right, trying to find a side wall. The water was still above their knees so neither saw the obstruction. Mercer hit it awkwardly, groped for balance and ended up knocking Lauren off her feet too.
He hit on his shoulder but the ground didn’t seem solid. More like landing on a patch of loose gravel than volcanic rock. He felt around under the water and picked up a handful of the pebbles.
“What is it?” Lauren asked.
Mercer shook water from the flashlight, cursing as it dimmed because it wasn’t waterproofed. He flashed the dying beam onto whatever he’d recovered from under the surface. Even in their rough form and shown in the poorest light there was no denying the green fire of the palmful of emeralds, the smallest of which was the size of an acorn.
“Oh my God!” Lauren felt around and came up with a double handful, letting them trickle from her fingers like marbles.
She scooped up more and let them fall across Mercer’s head. He did the same to her, twining mud and the precious stones into her wet hair, laughing.
He swiveled the beam and it just caressed a stack of small wooden casks. He half swam, half crawled over. The wood dissolved when he touched one of the crate’s lids. He worked it a second, opening a hole large enough to fit his hand. Inside, he recognized the soapy feel of the metal disks. He grabbed a bunch and tossed them to where Lauren was scooping mounds of emeralds over her legs. One of the coins landed on her lap. Like it was angered at being kept in the dark for so many centuries, the gold coin flashed harshly, a gilded spark like a mirror.
Lauren cried in delight. “It’s all here, isn’t it?”
The flashlight finally died, though neither cared as they hugged each other in the chilly treasure store. They finally made their way back to the surface, crawling up the stairs until they could see by the surface light spilling down from the entrance. They were soaked, covered from head to toe in mud that glittered where emeralds and other gems stuck to them.