The red dot on the monitoring screen was still moving, circling back and forth. Chen Hao stared at it for ten minutes, and his neck started to ache.

He turned his head and made a clicking sound.

“We can see outside now,” he said. “But if the ground collapses and the walls fall down, where will we run?”

No one responded.

Carl was taking apart the electric drill in the toolbox to clean off the dust, Susan was checking the newly entered probe numbers, and Nana was standing in front of the control panel, the camera flickering slightly, as if running some program in the background.

Chen Hao put the pen cap in his mouth, then spat it out. "I mean, when the alarm goes off, we know something's coming, or something's about to collapse. But the question is, what do we do after it goes off? Just stand here and wait for the collapse?"

Susan stopped writing. "You have an idea?"

“Yes.” Chen Hao stood up, walked to the projection map, and drew a line under the base with his finger. “Dig a tunnel.”

"Huh?" Carl looked up, nearly dropping the screwdriver into the drill bit.

"It's not about burying ourselves," Chen Hao rolled his eyes. "It's about building an underground shelter. In case something happens on the surface, we'll go down there and hide for a while. We'll come out again when things stabilize up above."

Susan closed her notebook. "Are you serious?"

“When have I ever been unserious?” Chen Hao said. “Last time I said I would use kitchen waste barrels to make a furnace, and you all said I was being ridiculous. But what happened? I blocked up three cavities and saved on materials.”

“That was grouting,” Susan said. “This is digging. Depth, orientation, load-bearing capacity, ventilation, drainage—none of these are simpler than building a wall.”

“I know it’s difficult.” Chen Hao scratched the back of his head. “But we don’t need to dig to the earth’s core. Just a shallow one, within ten meters will do. We’ll make a bend, avoid the rock layers, and create two exits, one leading to the workshop and the other to the edge of the forest to the north. We’ll keep it locked normally and open it when we need to.”

Carl put the drill back in, plugged it in, and tried it out. It made two buzzing sounds and then went out.

"This piece of junk can't even break down a wall," he said. "You think you can dig a mountain?"

"I'm not sending this drill to dig," Chen Hao said. "I'm just setting a direction first. We'll need to find the right tools to actually start construction."

Nana turned the camera around and said, "I can conduct a preliminary route simulation."

"You know how to do this?" Chen Hao was taken aback.

“The knowledge base contains standards for small bunker construction,” she said. “Combined with current ground-penetrating radar data, feasible route suggestions can be generated within three minutes.”

"Then hurry up and calculate." Chen Hao plopped back into his chair. "Even my rough sketches are crooked like earthworms."

Nana stood still, her eye light flashing from blue to green. A few seconds later, a semi-transparent route was projected onto the ground, starting from below the workshop's storage room, extending northwest, avoiding known soft areas, passing through sandstone layers, and finally splitting into two branches, one pointing to the east corner of the wall and the other to the woods on the north side.

"The main passage is recommended to be 3.5 meters deep," Nana said. "The cross-section is 0.8 meters wide and 1.2 meters high, which can accommodate two people evacuating side by side. Three reinforcement nodes are set up along the way, and a crossbeam structure is added to the top to prevent local collapse from affecting the whole."

"What about the exports?" Susan asked.

"The north exit is concealed behind bushes and covered with a movable cover plate. The surface is covered with fallen leaves and loose soil, and its infrared signature is close to that of natural ground. The east corner exit connects to the existing drainage ditch and is normally closed, but can be unlocked remotely in an emergency."

“That sounds plausible.” Karl leaned closer to examine the projection. “But did you draw this out of thin air? Are there really no stones underneath?”

“Based on the geological scan results from the past 72 hours,” Nana said, “the margin of error is less than five percent.”

Susan frowned. "But even if the route is fine, how will we proceed with the construction? We don't have a tunnel boring machine, support plates, or ventilation pipes. Are we going to dig with shovels? We won't be able to get through even by next year."

“Then let’s do it in sections,” Chen Hao said. “Let’s dig a test section first to see the actual soil conditions. If it’s all soft mud, we’ll change the plan. If it’s walkable, we’ll figure out how to get the tools.”

"How long is the test section?" Karl asked.

"Five meters," Chen Hao gestured. "Enough for us to test the soil, check the structure, and inspect the ventilation. It's not deep either, about two meters, so a person can stand there without bumping their head."

"We have to prevent collapse even at two meters," Susan said. "The last time we used grouting to stabilize the foundation, and now you're digging down again. What if it causes further settlement?"

“So we have to go slowly,” Chen Hao said. “We’ll dig half a meter a day, supporting the structure as we go. Didn’t Nana just come up with the support plan? We’ll add a crossbeam every 80 centimeters, according to the intervals she gave. We can use the leftover metal frame as materials, just cut it shorter.”

Carl shook his head. "Then someone has to go down and dig. Who will go? You?"

"I'm not afraid of soil," Chen Hao said. "I'm not made of tofu, how can I sprout if I'm buried?"

“You’re fat,” Carl said. “What if you get stuck? The people behind you won’t even have time to push your butt.”

"Get lost." Chen Hao tossed a pen over. "If you're not going, I will. We can't let Nana go to the fields, can we? She'll be like a tin can being simmered in heat if she goes in there."

Nana's eyelight flashed. "My body is not suitable for working in confined spaces, but it can provide real-time monitoring and structural warnings."

“That’s enough,” Chen Hao said. “Keep an eye on things, and call a halt if anything goes wrong. Susan will handle the material distribution, Carl will be in charge of the on-site support, and I’ll lead the digging. Five meters isn’t far; we can get it done in three days.”

Susan didn't speak, but tapped her fingers lightly on the table.

She knew Chen Hao was usually lazy; he would sit if he could stand, and lie down if he could lie down. But whenever something really happened, he was the first to speak and the first to take action.

He was the one who suggested blocking the foundation last time, he was the one who welded the furnace while squatting down, and he even got up in the middle of the night to refresh eleven pieces of equipment when upgrading the alarm system.

She sighed. "I can allocate the materials. But there's one condition—we must wait until tomorrow morning to run the model again with the data from the new probes we added today to confirm that the excavation won't trigger a chain reaction."

“Okay.” Chen Hao nodded. “Anyway, we don’t have all the tools, so let’s take this time to go over the plan again.”

Carl stood up, patted his pants, and said, "I'll go check the shovel now. The blade is all kinked; it needs sharpening."

“And that old chisel,” Chen Hao said, “did you find it?”

Carl glanced back at him. "At the bottom of the box, rusted like scrap metal."

"Don't throw it away," Chen Hao said. "It might still be useful."

Nana's projection was still on, and the underground lines floated silently on the ground. The green lines were stable, without flickering or interruption.

Chen Hao looked down and suddenly smiled.

"Do you think we should give this tunnel a name in the future?"

"What's your name?" Carl asked.

"Refuge One?" Susan said casually.

"Too formal." Chen Hao shook his head. "How about calling it a dog hole? Anyway, it's narrow and low, you have to lie down to get in."

"You want future generations to remember you for the rest of your life?" Carl said, "'That big shot dug a dog hole back then'?"

"That's called an escape route," Chen Hao corrected himself, "It sounds more professional."

“The dog hole sounds better,” Carl chuckled. “Then the announcement will come on: ‘Attention all personnel, the dog hole is open. Please evacuate in an orderly manner.’”

"Shut up." Chen Hao kicked his chair.

Susan glanced at the time. "We'll take turns on duty tonight to keep monitoring going. Tomorrow morning at six, we'll reassess the geological data and decide whether to start excavation of the test section."

“I’m on the night shift,” Chen Hao said. “I’m keeping an eye on that red dot to see what it is.”

“It’s still moving,” Nana said. “The trajectory hasn’t changed, it turns every twelve seconds, and it’s been going on for over nine hours.”

“It’s either a machine,” Chen Hao said, “or a mad animal.”

"The possibility of autonomous mobile devices cannot be ruled out," Nana said.

"Then why doesn't it come in?" Carl asked.

“They might not have noticed us yet,” Chen Hao said. “They might be waiting for an opportunity.”

“Or it can’t get in,” Susan said. “Our new alarm system changes the electromagnetic environment, and some devices will be affected by interference.”

“Whatever it is.” Chen Hao stood up and stretched. “What we’re doing now is ensuring that even if it tries to come in, we have somewhere to hide.”

He walked to the projector, squatted down, and slowly traced the tunnel route with his finger.

"Five meters isn't long," he said, "but as long as it's open, we'll have a way out."

Nana's eye light returned to blue and remained stable.

Susan began organizing the data tables she would need for tomorrow.

Carl carried his toolbox out, glancing back as he passed the door.

Chen Hao was still squatting there, staring at the glowing line, a smirk on his face, as if he could already see the day the tunnel would be completed.

No one spoke.

The projected light shone on the wall and flickered.

Chen Hao reached into his pocket, pulled out half a flattened biscuit, and took a bite.