The sky was just beginning to lighten as Shen Gun lifted the tent flap to look outside, seeing fog covering the mountains in all directions.

It somewhat resembled the foggy town where he lived.

Shen Gun sat cross-legged at the entrance of the tent, patiently waiting for the fog to disperse, and also patiently waiting for a marvelous sight.

He had visited Xiangxi many times before. In his “line of work,” traversing mountains and crossing waters from east to west was common. But even with just a pair of feet, though he came frequently, he hadn’t been able to explore many mountaintops. Places beyond his reach could only be regretfully abandoned. This time, however, hitching a ride with the Mountain Ghosts, he truly experienced the power of organization.

First, there was a convoy, making travel extremely convenient, driving to places where roads ended. There, they established Base Camp One, responsible for vehicle maintenance, management, and external communications.

Then, most people, carrying equipment and gear, hiked across mountains with impressive professionalism: they had topographic maps, mountain guides, GPS navigation and positioning, various unnameable detection instruments, and even deployed buzzing drones, leaving Shen Gun staring in amazement.

Midway, they set up Base Camp Two, leaving half of their equipment and gear there as backup—how thoughtful!

The final stretch required climbing a steep slope over half a li long at nearly 70 degrees. If it had been just him, it would have been impossible. But the Mountain Ghosts worked as a team—several advance climbers scaled up like monkeys, hammered in pitons, tied rope knots, and made a rope ladder. Thus, he managed to climb up, trembling but steady, stepping on the ladder.

How wonderful it would be if he could have such treatment every time! His research and explorations would surely reach new heights.

It was around midnight when they arrived at the top. The mountains were terrifyingly dark, with numerous wolf-eye flashlights and headlamps unable to illuminate beyond a hundred meters. There was only a vague sense that ahead lay a vast patch of extreme darkness, even blacker than the night itself. And, whether it was an illusion or not, he always felt there were faint howls and roars rolling within that blackness.

Meng Jinsong had people set up a security line, suggesting that going further would be dangerous. Everyone was to camp within the line and not cross it. He said that by morning, they would be able to see everything.

According to Second Shen’s private mutterings, the scene was extremely shocking and rare to behold.

So Shen Gun hadn’t slept well all night and even had a dream. In the dream, he was still searching for the box, but this time, he was groping in a vast, almost viscous darkness, with wails and roars swelling within the viscosity.

…

The mountain dwellers also began to wake up one after another. Sounds of brushing teeth and setting up cooking pots came through the thick fog. Some people turned on flashlights to see more clearly—but flashlights in white fog were useless except for draining batteries, so they were soon grumbled off.

Shen Gun swallowed and continued waiting, anxiously licking his lips. The thinner the fog became, the more nervous he grew, and the greater his expectations.

The sun seemed to leap onto the mountaintop all at once. Under the myriad rays of sunlight, the dense fog suddenly thinned, shrank, and disappeared within seconds, like a mask being ripped away, revealing everything beneath.

The noise around gradually diminished until only occasional pot and ladle clinks remained. After a while, even these sporadic sounds ceased. Shen Gun sprang to his feet and jogged to catch up with a group of excited mountain dwellers, crossing the first security line and arriving at the second.

The first security line was about a hundred meters from the cliff edge, while the second was only about ten meters away. Two people stood at the security line, maintaining order, not allowing anyone to proceed further. However, the area beyond wasn’t entirely off-limits—Meng Jinsong and Liu Guanguo stood just three or four meters from the cliff edge, pointing and discussing what was below.

Shen Gun quickly waved to Meng Jinsong: “Assistant Meng! Hey, Assistant Meng! It’s me!”

Hearing this, Meng Jinsong turned around, saw that annoying big face among the crowd, and frowned slightly. But the reputation of Seventh Aunt always worked wonders: since the man had come all this way, even if they didn’t bring Shen Gun to witness the Mountain Gallbladder, they should at least let him see this marvel.

Meng Jinsong smiled and nodded to the people maintaining order, indicating that this person could pass through.

Overjoyed, Shen Gun ducked under the security line and rushed forward in a few quick steps. He had intended to exchange pleasantries with Meng Jinsong, but his eyes were already glued to the sight, unable to turn or move away. After a long while, a sigh of amazement escaped his throat—

“How magnificent!”

Last night, he had thought this was just a mountain depression.

Mountains, after all, rise and fall. When you reach the highest peak, naturally, you have to go down. But he never imagined it would be a tiankeng.

In geography, the undulating mountains and valleys are collectively called “landforms,” and even mountain depressions and basins are included in this category because, with the ground as the boundary, mountains and valleys are at least above it, thus “positive.” Tiankengs are “negative landforms,” essentially large funnel-shaped collapses that sink deep underground, hence “negative.”

Tiankengs in China are mostly distributed in the southwestern karst landform-rich areas, where underground rock layers are predominantly water-eroded carbonate rocks. Over hundreds of millions of years, the underground gradually erodes into a honeycomb, and one day, reaching a critical point, it can no longer bear the weight above. With a thunderous boom, everything collapses, thus disappearing from the surface.

By academic definition, only those with both diameter and depth exceeding one hundred meters can be called tiankengs. Smaller ones are merely called “shafts.” To date, the world’s largest tiankeng is considered to be the Xiaozhai Tiankeng in Fengjie, Chongqing, with a diameter exceeding five hundred meters and a depth of over six hundred and sixty meters. Even by rough calculation, the bottom area would be several hundred mu.

The Tiankeng before his eyes had a smaller opening diameter than the Xiaozhai Tiankeng, but it was still estimated to be three to four hundred meters. What was more incredible was that the opening wasn’t exposed to the sky. If an airplane flew overhead, the people on board would never discover there was a tiankeng here, thinking it was just an ordinary mountain depression, because above the opening, it was as if a giant green cover had been pulled, concealing this enormous deep hole.

Shen Gun swallowed several times in succession and got goosebumps all over.

Standing close, he could see very clearly that the giant cover, from a distance, appeared as a dense green with light emerald hues, but in reality, it was sparse and perforated, formed by countless intertwining vines and branches. But how could vines and branches grow horizontally, and with such astonishing length that they could cover the opening of the pit?

This must have been artificially guided, but another question arose: how much manpower would that require, and what an enormous project it would be!

He squatted down to look carefully, and this one look truly made even his hair roots stand on end.

It was indeed guided by human effort: around the nearly circular pit opening, at intervals, there were long brackets wedged into cliff crevices. The brackets were covered with verdigris, very likely made of bronze—if the guess was correct, it was probably in ancient times that someone, using bronze brackets wedged into the rock wall as support points, pulled ropes and tied knots, like setting up a gourd trellis in a farmyard, creating a giant net across this pit opening. Then they guided the vines and branches to twine along the rope net, climbing and growing until they all grew together, forming a natural green cover.

Many years later, the original net ropes had all rotted and fallen, leaving only the bronze brackets, but the interconnected vines and branches remained strong.

…

No, that’s not right either. Shen Gun shook his head, rejecting his conjecture: how long would these vines have to be? The world’s longest known plant is the rattan palm, which can grow up to four hundred meters if there is sufficient length for it to climb. But that’s in tropical rainforests. Xiangxi doesn’t have the right climate conditions. Even if it did, according to growth rates, it would take nearly a thousand years to reach a hundred meters in length. During that time, there would be countless geological disasters, droughts, and floods. How could you ensure it would grow precisely into a “lid”?

The murmurs of Meng Jinsong and Liu Guanguo drifted to his ears.

Meng Jinsong: “The drone can’t fly?”

Liu Guanguo: “It can’t. The magnetic field here is somewhat peculiar; electronic devices are all a bit erratic.”

Meng Jinsong: “What about SRT?”

SRT is a single-rope ascending and descending equipment fixed to rock walls, also known as “single-rope technique.” Simply put, it allows free ascent and descent on a single rope, widely used in cave exploration and underground expeditions.

Liu Guanguo: “It’s just for show. You know, there are the flying foxes.”

Meng Jinsong: “Parachutes and wing suits won’t work either?”

Liu Guanguo: “The visibility down there is too low, and the terrain is complex, making operation extremely difficult. Besides, we’re also afraid of the flying foxes.”

Shen Gun thought the name “flying fox” sounded familiar, as if he had heard it somewhere before.

Meng Jinsong sighed: “See, after so many years, with technology developed to this extent, we still have to use Granny Duan’s old methods.”

Liu Guanguo echoed beside him: “Exactly.”

With too many puzzles, Shen Gun couldn’t help but ask: “Assistant Meng, is this…”

He didn’t know how to describe the interconnected vines before him: “All the work of the Mountain Ghosts?”

Meng Jinsong shook his head: “That I don’t know. It has never been recorded in the Mountain Ghosts’ chronicles.”

“Then… do the Mountain Ghosts maintain and take care of it regularly?”

Meng Jinsong continued to shake his head.

No one comes to maintain it. In the Mountain Ghosts’ perception, the location of the Mountain Gallbladder is almost a “forbidden zone,” similar to “unexplored mountains.” Moreover, the mountain terrain is treacherous, the forests deep, the paths dangerous. Just reaching this cliff was already extremely difficult. Even mountain dwellers who had lived in Xiangxi for a long time rarely came to explore, let alone provide “maintenance and care.”

Perhaps thousands of years ago, the first ancestral grandmother, after hiding the Mountain Gallbladder, also arranged this exquisite barrier that deceived all living beings with astonishing skill?

Meng Jinsong walked a few steps forward, almost touching the cliff edge, and beckoned to Shen Gun: “Come here and look.”

The altitude of this mountain was at least eight hundred, if not a thousand meters. Even in fair weather, there was inevitably some wind. That position truly made one tremble with fear and dizziness. Even someone like Shen Gun, who had experienced many major challenges, couldn’t help but feel terrified.

He shuffled over.

Meng Jinsong pointed downward: “Look carefully. It might be a bit dark. Try from different angles, and you should be able to see the mountain peak.”

Mountain peak? There’s a mountain peak inside the cave?

Shen Gun almost forgot his fear, rubbing his eyes several times as if rubbing could increase clarity. He frequently shifted his position, and when he finally saw clearly, he blurted out: “Peak forest?”

Meng Jinsong nodded, raising his hand to indicate a position: “If you’ve been to Wulingyuan, you should have seen the most famous attraction there, the sandstone peak forest. This is similar. Below was originally a low-lying mountain basin with a small peak forest, but later, I don’t know how many tens of thousands of years ago, the ground collapsed with a boom…”

His palm fell sharply downward: “The entire peak forest went down, sank.”

After a pause, he sighed: “It’s a pity, because this peak forest had unique shapes. From certain angles, it looked like a beautiful woman’s head on a slender neck.”

Shen Gun didn’t quite understand. He was still immersed in the shock of “sank”: this tiankeng was deeper than the Xiaozhai Tiankeng. Going down from the cliff, a thousand meters would not be enough.

Meng Jinsong pointed again at that huge green cover: “The magnetic field here is problematic; drones can’t be released. Otherwise, we could do an aerial photograph to give you an intuitive concept: it is said that this green vine cover is not chaotic but has been guided into a certain shape. Some places are dense, some sparse. If you stand at the bottom looking up, it’s like seeing a giant eye floating in the sky.”

This scene was too magical. Shen Gun felt a chill all over his body.

Meng Jinsong’s tone remained unhurried: “The vines forming the pupil part of this eye are quite interesting, different from elsewhere. They seem naturally photophobic. When the sun comes out, they curl up and retreat to their surroundings, as if opening their eyes, creating a gap to send sunlight down. You know, it’s light-deficient down there. And at night, they extend and stretch out again, covering the pupil. Isn’t it like a person opening their eyes during the day and closing them at night? And when this eye closes, due to the day-night temperature difference, dew mixes with the sap from old vines and drips down, very viscously. We have a vivid metaphor for it, called ‘pupil oil drip.'”

Shen Gun didn’t know how to respond. After stammering for a while, he swallowed his words.

He imagined the scene of vines curling and retreating to the surroundings during the day: that ray of sunlight let in seemed like a profound gaze from heaven.

“The sunlight shining in at that angle can only cover one peak, and that peak happens to be the one hiding the Mountain Gallbladder. So, only the flowers on that peak can bloom. On other peaks, due to the year-round lack of light, forget about flowers—even green plants are withered. We have a verse, ‘Beautiful woman’s head, hundred flowers shy,’ describing exactly this scene.”

Meng Jinsong seemed to be talking to himself: “This place is too remote, almost no one can find it. Even if found, they can’t go down. The ropes brought by herb gatherers are usually only a few dozen meters long. Besides, there are packs of flying foxes down there.”

“About eighty years ago, one of the Mountain Ghost leaders, Granny Duan Wenxi, climbed down. It is said that the rotting branches and leaves at the bottom were one to two meters thick. And because the sunlight, humidity, depth, and temperature were completely different from the surface, the environment below formed its own self-contained and unique ecosystem. Granny Duan’s diary mentioned encountering white rats weighing over twenty jin down there…”

This, Shen Gun did know: species inside tiankengs, due to the enclosed environment, face simple yet intense survival competition. They strive to evolve to adapt to the environment. Take the common brown bamboo in the south, for example. Generally only about two meters tall, but in tiankengs, to compete for that bit of sunlight that penetrates down, they can only grow desperately, often reaching seven to eight meters high, because if you don’t grow desperately, you only have one path: death.

Living isn’t easy, not just for humans, but for plants too.

Meng Jinsong stopped there. He moved closer to Shen Gun and lowered his voice: “Cutting open the mountain to extract the Mountain Gallbladder is done here, Mr. Shen. This isn’t setting up a stage for a performance for people to see. Every step is life-threatening. I’ve shown you the place. If you dare to go down, then go down. I will offer kind advice, but I will not stop you.”