The final base camp stood at the edge of a karst region so quiet it seemed deliberately cut off from human voices. Several tents had been set up on a flat stretch of ground surrounded by dense green trees. Beyond those trees, limestone walls rose high, their wet surfaces overgrown with moss. A thin mist hung between the trunks, while the air carried the smell of soil, old leaves, and water whose source could not be seen.
Luweng Ombo's cave mouth opened before the base camp.
The vertical shaft was roughly fifty meters in diameter. The edge of the chasm looked like a dark circle forcibly carved out of the limestone hill. It reached a depth of two hundred forty-six meters, but the bottom could not be seen from above. Morning light struck the rock walls, then vanished before reaching the darkness below.
There was no sound of vehicles. No conversations from the locals. Even the birds around the opening seemed to choose to fly farther away. Every so often, wind rose from the bottom of the chasm, damp and cold, carrying the scent of wet stone that made the skin on their arms prickle.
The day before the exploration, Senja stood near the temporary safety barrier they had installed around part of the chasm's edge. She checked the map, the equipment list, and the permit documents stored in a waterproof folder.
“We've already received special permission from the local government and the village authorities,” Oscar said as he read through a copy of the documents. “Including approval from the area's management. So no one can accuse us of going down there in secret.”
“If we go down without the proper skills, that permit won't help much,” Senja replied.
She pointed to the coils of rope, safety harnesses, helmets, headlamps, descenders, ascenders, carabiners, and communications gear arranged on the tarp.
“Luweng Ombo isn't a place to test your courage. We'll be using Single Rope Technique, or SRT. We have to master every movement. Rope checks, anchor points, communication, and emergency procedures cannot be skipped.”
Oscar stared at the chasm. “Are you looking at me when you say that?”
“I'm looking at everyone.”
“Which means you are looking at me.”
On the other side of the base camp, Ucok was setting up a tent beneath a large tree. He pulled the guy lines tight, hammered in the stakes, then turned toward them.
“If Mas Oscar wants to go down first, I'll help hold the rope from up here.”
Oscar pointed at him. “That's not support. That's an insult wrapped in politeness.”
“The important thing is, it's wrapped, Mas.”
Senja let them trade barbs. She would rather hear a little bickering than let the tension build with nowhere to go. But when their voices died down, the echo from inside Luweng Ombo could be heard again.
Ucok stopped driving in the stake.
A small sound came from the hole. Maybe a falling rock. Maybe a drop of water striking another surface. The sound slid downward, bouncing from wall to wall, then returned as a faint echo that lasted far too long for something so simple.
“A rock?” Oscar asked.
“Could be,” Senja replied.
“Could it also be something else?”
Senja did not answer right away. She picked up a small pebble from the ground and dropped it into the chasm. They waited.
One second.
Two seconds.
Then came the sound of echoes from the depths. Not once, but in succession, as if the pebble had struck several planes of rock before finally disappearing.
“Even the smallest sound will bounce off the bottom,” Senja said. “Don't shout near the cave mouth. We'll communicate using codes and the radio.”
Ucok nodded. “Okay. So if I get scared later, I'm not allowed to scream?”
“You are,” Senja said. “But make sure it's part of an emergency code.”
“Wow, what a hassle. I was just about to get scared.”
The three of them then sat on an equipment crate. The sun began to sink behind the hill, but the remaining light could not dispel the darkness that seemed to cling to Luweng Ombo's mouth. Their exploration plan was complete. The next morning, they would descend, inspect the points marked on the old map, follow the watercourse, and search for a clue to the Guardian Spring.
Oscar opened a notebook whose cover had begun to peel. “If this legend is true, the relic isn't merely a royal object.”
Ucok poured water from a bottle into a metal cup. “Then what is it? Something that gets angry if it isn't given offerings?”
“According to the records we have, the relic was believed to turn its owner into a leader.”
Senja looked at the notebook page. “That doesn't mean every owner became a good leader.”
Oscar nodded. “In the hands of the right person, the Guardian Spring grants wisdom, humility, justice, and inner peace. At least, that's what people believed.”
“And in the hands of the wrong person?” Ucok asked.
Oscar closed the notebook for a moment. “The relic removes the moral brakes. Its owner begins daring to do extreme things that ordinary people would still consider taboo. Power makes them see threats everywhere. Afraid of losing the throne, they attack first before they are truly attacked.”
Wind moved through the trees. The leaves stirred in unison, but the mist above the chasm remained still.
“So the relic doesn't make people evil,” Senja said. “It magnifies whatever is already inside its owner.”
“If that's the case,” Ucok said, “even good people have to be careful. Sometimes we don't know what's in our own hearts until we're given power.”
Senja studied him for a moment. Ucok had spoken without joking. Then he went back to checking the tent ropes, as if he did not want the conversation to linger on his face.
According to the family records and historical fragments they had gathered, the Guardian Spring had been passed down through generations within the Majapahit royal family. It was no wonder the kings of Majapahit were remembered in such different ways: some were cruel, some wise, and some changed between the two after coming face-to-face with power.
At the end of the Majapahit era, Brawijaya V was believed to have made a pilgrimage to Luweng Ombo. It was not merely a routine retreat for meditation. He had come with a heavier purpose: to bury the Guardian Spring and lock its power away in the depths of the cave.
“If Brawijaya V really locked it away here,” Oscar said, “then the relic is still beneath us.”
“Not necessarily,” Senja replied.
Oscar raised an eyebrow. “We already have the symbol, the watercourse, the villagers' stories, and the records about Brawijaya. What else do you need?”
“Proof that this place is still locking something away.”
Senja opened the old map. She spread it across the crate, holding down its four corners with carabiners. An eight-pointed sun ornament appeared at the bottom of the map. At its center was a circle bearing intricate carvings that resembled an eye watching from behind the stone.
“Tomorrow, we're not just looking for the relic,” she said. “We're looking for the reason people believe the water here is capable of locking it away.”
Oscar stared at the symbol. “And if the door really exists?”
“Don't open it until we know what's keeping it closed.”
For a while, the only sound was that of the forest. Then a different echo rose from the bottom of the chasm. Deeper, heavier, like something moving far beneath the layers of rock.
Ucok switched off the headlamp he had been testing. “That wasn't the sound of a falling rock.”
Senja closed the map.
“We go down tomorrow,” she said. “No one goes near the edge of the chasm alone tonight.”
In another corner of the base camp, screened by a line of trees and a rocky slope, another expedition group stood in silence. Their equipment was newer, their tents dark-colored, and several of their crates bore writing in Dutch.
A woman stood at the front. She was around thirty, with dark blond hair tied low and a calm, unreadable face. She held a pair of binoculars, but she was not pointing them at the chasm. Her gaze was fixed on Senja, Oscar, and Ucok's base camp.
Her name was Sophia Adriana.
She reached into her pants pocket and pulled out a flat metal plate no larger than her fist. An eight-pointed sun symbol was engraved on its surface, with intricate carvings at the center—exactly the same as the mark on Senja's map.
The chill of the metal spread across her skin, but what made her hold her breath was not the temperature. It was the faint pulse she felt from behind the carvings.
Tomorrow, the cave exploration would begin. They would descend into the darkness, following the watercourse toward a place that had been hidden from the world for centuries. Sophia stared at the symbol without blinking. This time, the door would not wait much longer.