Chen Hao stared at the crack in the rock in the distance, his fingers still covered with debris from digging. He didn't move, just squinted, as if afraid the crack would close up in the blink of an eye.

"The cavity you mentioned earlier," he finally spoke, "was it like a hole carved out of the mountain's belly?"

Nana stood half a step to his side and slightly adjusted the angle of the optical lens: "The structural features match the definition of a karst cave, but it is not confirmed whether it is connected to a deep underground system."

"So, it could be a dead end, or it could lead to the Earth's core?" He grinned. "Then I'd better be careful not to step into lava and end up as a skewer, saving myself a meal."

“There are currently no signs of volcanic activity,” she said, “but the internal stability needs to be verified on-site.”

"Alright, anyway, these plots of land outside aren't exactly easy to deal with." He dusted off his pants and took a step forward. "Since it's all about taking a chance anyway, I might as well go to the mountains and try my luck."

They walked along the gentle slope toward the crevice. The closer they got, the more they could see that the crevice wasn't formed by natural weathering—the rocks on both sides were cut apart as if by a knife, the edges were too neat, as if someone had made a cut with a knife.

The vines were tightly intertwined, and the old roots were tangled, covering most of the entrance. Chen Hao reached out to pull, but as soon as he exerted force, the whole branch and leaves shook, and soil fell down in a rustling sound.

"Don't force it." Nana raised her hand, and a thin blade slid out from her wrist. "This way of wrapping plant fibers can easily cause a chain reaction of loosening."

"You even brought scissors?" He took a half step back. "I thought you'd just flick out nail clippers at most."

The blade sliced ​​silently into the vines, leaving a clean cut. Her movements were slow, but each cut landed precisely on a node of the main stem, clearing a gap large enough for a person to crawl through in just a few strokes.

Chen Hao peered inside. It was pitch black and bottomless, and the wind blowing out carried the smell of stones soaked in water.

"If this is a monster's den, we can still retreat now." As he spoke, he bent down to pick up his backpack and took out his headlamp and rope.

"If a life signal is detected, I will issue an early warning." Nana retracted the probe into her body, and a ring of lights illuminated on her shoulder. "The lighting system is activated."

"With this setup, you could rent it out and film an adventure documentary." He put the headlamp on his head and tested the switch. "Is the rental fee by the hour or by the life?"

“There is no rental service available at the moment.” After saying that, she stepped into the cave entrance first.

It was more spacious inside than he had imagined. The floor sloped downwards, and the stone surface, washed by water, was a bit slippery. Chen Hao had only taken two steps when he slipped and almost fell to his knees, but luckily he grabbed the wall to steady himself.

"Ouch, my back..." He rubbed his tailbone. "This place doesn't even have a handrail. It's so inhumane."

"I suggest lowering your center of gravity and taking small steps." Nana walked ahead, the light shining far, casting a long shadow against the rock face. "The current slope is about twelve degrees, and the coefficient of friction is low."

"Couldn't you just say something as simple as 'Walk slowly on slippery roads'?" he panted as he caught up. "You have to make it sound like you're taking attendance in class."

The passageway gradually narrowed, then suddenly widened. The overhead height increased, allowing me to stand upright. The air circulation was good; there was no feeling of stuffiness.

"Oxygen levels are stable." Nana glanced around. "Carbon dioxide concentration is 0.04%, which is within the normal range."

"It sounds even healthier than my cholesterol levels from my last physical exam." He looked around. "But you said no one's ever been here, so it looks... like someone's tampered with it?"

There are several obvious scratches on the rock face, as if they were made by tools. There are also traces of piled-up rubble on the ground, which does not look like a natural collapse.

“Other biological activity cannot be ruled out,” she said, “but there are no recent records of mobile heat sources.”

"Could it be that the previous resident cleaned the house before leaving?" He kicked a flat stone at his feet. "They're quite particular."

Further in, shallow grooves began to appear on the ground, crisscrossing like channels formed by long-term water erosion. Some places still bore damp marks, reflecting a faint light.

“There’s been water flowing through it.” Chen Hao squatted down and touched it. “And it wasn’t just a matter of a day or two. It would take several years of flowing water to carve out this kind of groove.”

“I support your judgment.” Nana looked down and scanned the area. “Mineral deposits indicate that there was once intermittent underground runoff here.”

"So that means we can grow vegetables when it's dry, but when the water comes in... we have to move?" He stood up. "It sounds like renting a farmer's house, which floods in the summer and is drafty in the winter."

“If it is to be used for planting, drainage and moisture protection solutions need to be evaluated,” she said. “Currently, it is not suitable for direct cultivation.”

“I know, I’m not really expecting to move in right away.” He took a few steps forward, his voice echoing in the cave. “But the problem is, at least we’ve found a place that can shelter us from the wind and rain. Those other plots of land outside would crumble in the wind and rot in the rain; none of them are as sturdy as this place.”

“Structural safety is still being monitored,” she cautioned. “The top rock layer is on average 1.8 meters thick, and there are cracks in some areas.”

"1.8 meters? That's way thicker than my head." He looked up. "Besides, I don't run into things every day."

As soon as he finished speaking, his feet suddenly lost their footing.

"Depend on!"

A loose stone slab collapsed halfway, causing him to sink a bit, his left leg getting stuck in the gap, and he almost twisted his ankle.

"Don't move." Nana immediately turned around, the light locking onto his location. "The load-bearing structure may have been damaged."

"I don't want to move!" he gritted his teeth, "but this leg won't obey me!"

She stepped forward, knelt on one knee, and reached into the gap. The mechanical knuckles precisely gripped the edge of the stone slab, and with a slight exertion, lifted the stone that was pressing down on his calf.

Chen Hao pulled his leg out and sat on the ground, catching his breath.

"This landlord is ruthless, giving such a huge pit as a greeting gift." He swung his foot. "Luckily I'm fat, so I can hold it in."

“There is a hidden fault zone in this area,” Nana continued scanning. “I suggest detouring or reinforcing the area before proceeding.”

“We can take a detour, but we need to see if there’s a better way ahead.” He leaned against the wall to stand up. “We can’t just say it’s fate that we’re not allowed to enter the cave because we fell down.”

He dusted himself off and turned his headlamp back on. The beam swept across the passage ahead, and he could vaguely see that the space beyond the corner was larger, and the ground was smoother.

“Look over there,” he said, pointing to the corner. “Isn’t there something like a platform?”

Nana focused her observation: "It appears to be a natural stone platform, with a relatively level surface and an area of ​​approximately three square meters."

"Three square meters? That's enough for me to lie down and turn over." He grinned. "Maybe I can even set up a pot and cook some instant noodles to celebrate the successful land reclamation."

“There is currently no supply of flammable materials,” she said, “and the ventilation is insufficient to remove open flame fumes.”

"Can't you let me dream for a while?" He waved his hand. "A person has to have something to look forward to in life. Today's hope is that we've finally found a place where we don't have to be exposed to the sun, get soaked by the rain, or worry about the ground collapsing in the middle of the night."

He took two steps forward and then suddenly stopped.

"Wait a minute." He looked down at the ground. "This stone... isn't it a little different?"

When the light shines down, the stone surface has a faint bluish-gray tint, interspersed with tiny white spots, as if it has been polished by something.

Nana crouched down and lightly touched the surface with her fingertips: "This is a calcium carbonate deposit, which is common in long-term water erosion environments."

"So, this place used to have water, and it flowed quite evenly?" He looked up. "Where water flows, the soil can thrive—if I remember correctly?"

“Theoretically, it makes sense,” she said. “But soil formation requires the accumulation of organic matter, and no humus components have been detected so far.”

“But as long as there is water, there is hope.” He took a deep breath. “Insects can come, grass can grow, and people can live. What we lack now is time, not space.”

He continued walking forward, his steps much steadyer than before. Turning the corner, the view suddenly opened up before him.

A space, not too large but large enough to accommodate several people, unfolded before them. The surrounding rock walls curved inwards, and several small holes at the top let in a little sunlight, like a tattered curtain.

The ground is flat, with a slight depression in the center, like a natural small depression.

“This place…” Chen Hao stood in the middle and walked around it. “It can be used as a living space, a storage space, and a warehouse.”

“The structural stability is better than the external site selection.” Nana finished scanning. “No immediate risk of collapse has been found.”

“It’s settled then.” He plopped down on the stone platform. “This will be our new base from now on. Let those lousy places outside do whatever they want, we’re not going to put up with them anymore.”

“Further surveying and risk assessment are still needed,” she said. “It is recommended to set up temporary markers and return to base to retrieve equipment before proceeding further.”

“Marking it is easy.” He took out a charcoal stick and drew a crooked arrow on the edge of the stone platform, with the word “treasure” written underneath.

“What does this mean?” she asked.

“My precious treasure.” He patted the stone. “Our first piece of real estate.”

He was laughing when he suddenly felt a slight tremor at his feet.

Looking down, I saw that the edge of the stone slab I had just stepped on had a thin crack.