The blue light emanating from the energy core stopped twitching, becoming as steady as a repaired old air conditioner. The vibrations within the rock cavity ceased completely, and even the air itself quieted down, as if the impact that had nearly blown people away was merely a collective hallucination.

Nana opened her eyes; the data stream on the screen was scrolling rapidly. "System has entered standby mode, defense protocols are off, unauthorized data residue has been isolated, and there is no active risk." She paused, "Current status is stable; safe evacuation is possible."

No one moved immediately.

Carl sat on the ground, leaning against a pile of rubble, his fingers still resting on the power box's connector, as if afraid it might suddenly explode. Susan held the protective bag; the crystal lay quietly inside, its surface cracks still visible, but its light was even and no longer flickering. She glanced down at it, then looked up at the core, her lips moved, but she didn't speak.

Chen Hao tilted his head back, the back of his head against the wall, his hand still hanging in mid-air, not far from the button of the temporary device. He blinked, then suddenly smiled.

"Hey."

He slapped his leg; the sound wasn't loud, but it was exceptionally clear in the quiet cavern.

"This thing really won't explode?"

Carl turned to look at him. "Have you tried restarting your life?"

"I haven't tried it, but right now I feel like a surviving bug."

After he finished speaking, he stood up, stretched his limbs, and his bones cracked twice. Then he walked over and slapped the wall three times, the rhythm exactly the same as when he activated the rhythm interference earlier.

"That's it for the day, brothers. We didn't run away; we just finished our work and left."

Susan finally breathed a sigh of relief and shifted the protective bag onto her shoulder. Carl slowly got up, picked up the scattered tools, and casually stuffed the broken capacitor into the side pocket of his backpack.

Nana stood still, the optical lens scanning the four people. "The return route has been updated. It is recommended to avoid the southeast rift valley area, as radiation levels are still above the standard."

"I'll listen to you." Chen Hao tugged at the collar of his protective suit. "These clothes really stink after wearing them for a while. It would be best if we could go back and take a shower as soon as possible."

"Assuming there's still water at the base," Carl muttered.

“Whether there’s water or not isn’t important,” Chen Hao said while checking the storage module on his belt. “What’s important is whether the door can be opened. If even the main door collapses, we’ll have to knock on the door and shout, ‘Is anyone home?’”

Susan rolled her eyes at him. "You still want to knock?"

"Or climb out the window? With my size, if I get stuck, I'll become a permanent resident."

Carl bent down to finish tidying up the last circuit board, then paused. "We've been messing around here for ages, and nobody knows what's going on outside. Has the tsunami receded? Have communications been restored? Or maybe…"

He didn't finish speaking.

The three of them looked at him.

“Or,” he said in a low voice, “when we came back, we found that nothing was left.”

The air seemed to sink a little more.

Chen Hao squatted down and tightened his shoelaces again. He lowered his head and tugged at the knot with his fingers.

“If that’s the case,” he looked up and grinned, “then the four of us will build an even better one from scratch.”

Susan snorted, "You're quite optimistic."

“If I’m not optimistic, who is? You? Karl? Or Nana?” He pointed at the robot. “She can’t even change her expression.”

Nana calmly said, "My facial module has a 62% failure rate, making it unable to simulate complex emotions."

“Look,” Chen Hao spread his hands, “even the robots are worse off than us, at least we can still laugh out loud.”

Carl shook his head, slung his bag over his shoulder, and carried the newly assembled signal booster in his hand—the casing was made from an old battery box, and the antenna was a spiral made from discarded wires, which was ridiculously ugly, but the indicator light was on green.

“It’s a bit ugly,” he patted the device, “but it works. More reliable than some of those who just make empty threats.”

"Hey, I was just trying to boost morale," Chen Hao said, raising his hands in surrender. "Besides, who was it that said we needed to rebuild? Wasn't it me?"

“You’re just being stubborn.” Susan adjusted her bra strap. “But… at least for now, the planet won’t swallow our home anymore.”

Nana stepped forward, her arm projecting a blue path that extended from the current rock cavity, bypassing three high-risk areas, and pointing directly to the surface exit.

"The journey is expected to take five hours and seventeen minutes, and you will need to pass through two landslide-prone sections along the way. It is recommended to maintain formation."

"Understood." Chen Hao stood at the front. "I'll lead the way, Carl will bring up the rear, Susan will protect the crystal in the middle, and Nana will report on the road conditions at any time."

The column began to move.

Before leaving the core hall, Chen Hao glanced back. The blue sphere of light still hovered in the air, slowly rotating like a tamed heart. The door slowly closed behind him, the heavy metallic clanging sound like a period at the end of a journey.

The passageway was much quieter than when we arrived.

There were no alarms, no tremors, and no sudden energy pulses. Only the sound of footsteps echoed between the rock walls, one after another.

"Do you think someone up there might be waiting for us?" Susan suddenly asked.

“Definitely.” Chen Hao said without turning his head, “Old Wang on duty, Old Li who cooks, and Xiao Zhang the electrician who always complains about how much electricity we use.”

"If they knew we actually fixed the core, they'd probably think we were joking."

"The first thing we'll do when we get back is turn the radio on," Chen Hao said. "Play an old song, preferably one that's so loud it keeps people awake."

"Are you sure you're not doing this to get revenge on everyone?" Carl said from behind.

"This is called spiritual reconstruction."

Susan chuckled softly and hugged the protective bag tighter.

Nana walked in the middle, her optical camera constantly scanning the road ahead. "There is a minor landslide 30 meters ahead, but it is passable. We recommend staying on the left side."

"Received." Chen Hao raised his hand to signal to slow down.

They passed through the narrow gap one by one. Chen Hao's shoulder scraped against the rock wall, his protective suit ripping, but he didn't stop.

"My clothes are torn." He looked down at himself. "I need to change when I get back, otherwise I'll look too pathetic."

“You’ve been looking rather disheveled,” Carl said, catching up.

"But I was a successful mess."

The passage gradually ascends, and the slope becomes gentler. The air begins to move, carrying a slight breeze.

"We're almost at the ventilation level," Nana said.

"So, if we go any higher, we can receive external signals?" Susan asked.

“Theoretically, yes,” Nana replied, “but currently no valid communication frequency bands have been detected.”

No one spoke.

Chen Hao touched the communicator; the switch had been broken for a long time, but he still pressed it out of habit.

No response.

"Everyone's probably busy repairing their houses," he said, "and doesn't have time to send messages."

“Maybe…” Karl began.

"Goodbye," Chen Hao interrupted. "We're going back with good news now, don't keep reciting eulogies along the way."

"I'm just stating the facts."

“Facts can be changed.” Chen Hao glanced back at him. “Three hundred years ago, someone left this system behind, and nobody thought it could be repaired. We’ve repaired it now. So don’t tell me things like ‘it might all be gone.’”

Susan whispered, "You weren't this talkative before."

“When you’re under a lot of pressure, you always come up with new skills,” he shrugged. “For example, I can still think about what to have for dinner while I’m walking.”

"Is food all you can think about?"

“You need to be well-fed to have the strength to rebuild,” he said confidently. “The first meal must be meat, canned stewed potatoes, and a bowl of hot soup.”

Carl sighed, "Your goal is too low."

“It’s low-key but practical,” Chen Hao laughed. “It’s better than shouting slogans, like ‘For the future of humanity’—who can understand that?”

At the end of the passage, a sloping staircase appears, the rusty metal ladder fixed to the rock wall, leading to a half-open inspection door.

Nana pointed to a sliver of gray light shining through the crack in the door. "The exit is imminent; preliminary environmental testing is underway."

Chen Hao was the first to step onto the ladder. After taking two steps, the iron ladder creaked.

"Can this thing hold up?"

“People lighter than you have all been up there,” Carl said from below.

That's a personal attack.

I'm stating the facts.

Chen Hao climbed to the top and pushed the door. Half of it was rusted shut. He kicked it hard, and the door sprang open, dust falling in a flurry.

It was dusk outside, the sky was gray and hazy, the clouds hung low, but it wasn't raining.

He poked his head out and looked around.

On the distant horizon, the outline of the base was still visible. The towers hadn't collapsed, and the main building complex remained intact, though some cracks appeared in the exterior walls, and a few roofs had collapsed halfway. The solar panel arrays were leaning haphazardly, but most of them were still standing.

"Hey," he called back, "Still here."

Susan climbed up and took a look, said nothing, but her shoulders relaxed.

Carl was the last to come out, and the first thing he did after getting his footing was to turn on the signal booster. The indicator light flashed a few times, then stayed on.

“There’s a weak signal,” he said, “but no content, just noise.”

"At least it's not dead." Chen Hao took a deep breath; the air smelled of burning and damp earth.

Nana stood at the doorway, expanding the scanning range. "Three life signals detected, located in the main living area, weak but persistent."

“Someone is alive,” Susan said softly.

"Of course," Chen Hao said, cracking his knuckles. "Otherwise, who would open the door for us?"

He strode forward, his footsteps crunching on the gravel.

The others followed.

After walking less than twenty meters, Chen Hao suddenly stopped.

There was a crack in the ground ahead, not wide but very deep, with charred edges as if it had been melted by high temperatures. In the middle of the crack lay a broken mechanical arm, the same model as Nana's.

He crouched down, picked up a small piece of wreckage, turned it over and looked at it. The serial number was blurry, but he could tell that it belonged to an early exploratory robot.

“This isn’t ours,” he said.

“It’s not the model issued by the base either.” Nana walked over, glanced at it, and said, “The production batch was 320 years ago and it has been discontinued.”

"Then how did it get here?"

No one answered.

Chen Hao put the fragments into his pocket and stood up.

“Keep going,” he said. “Let’s go back first.”