When Chen Hao woke up, he was still wrapped tightly in the blanket. He turned over, his head peeking out from the edge of the canvas, his nose bumping against the wall. The room was quiet; only embers remained in the stove, and the heating pipes were silent. Nana's projector sat above the workbench, its screen dimmed, as if asleep.

He sat up, rubbed his shoulders, and muttered, "I wish there was some food down there."

He paused for a moment after speaking. It sounded so real, as if he'd heard it somewhere before. He stared at the floor for a while, then suddenly remembered that the floor tiles in the control room felt a little loose when he stepped on them before going to bed the night before. He hadn't paid attention then, but now, thinking back, it seemed like he could still feel a slight vibration.

"Hey." He reached out and nudged Nana's projection.

The projector flickered and then lit up again. "Non-standard wake-up command detected. Enter working mode?"

"Stop with all this fancy stuff," Chen Hao said. "Did you record any noises down there before you turned off the lights last night? Like over in the storage room, the floor shook a little."

Nana paused for two seconds, and the data stream began to scroll. "At 3:17 a.m., a slight vibration of 0.8 seconds occurred below the southeast corner, and the frequency characteristics are consistent with the displacement response of a metal structure. Combined with the back-scanning of the ground-penetrating radar, it was confirmed that there is a closed cavity eight meters underground, with a size of approximately twelve by nine meters, which is preliminarily identified as an old-style storage space."

"I knew it!" Chen Hao slapped his thigh. "I knew it wasn't just my imagination."

"It is recommended to conduct a structural safety assessment before restarting," Nana advised.

"It's not even open yet, what's the point of commenting on safety?" Chen Hao had already stood up and was walking towards the control room in his slippers. "Anyway, we're just sitting around doing nothing, digging something out is better than just waiting."

He lifted the carpet in the storage room, revealing a metal plate with bolts. It was heavily rusted, but the four corners were still clearly sealed shut. He crouched down and tapped it; the sound was dull, indicating there was indeed space underneath.

"It has to be able to be dismantled," he said.

"Available resources: one hydraulic jack from a scrapped vehicle, one set of thermal cutting tools, and three sections of support beams," Nana reported. "It is recommended to limit the operation window to within two hours to avoid affecting the building's load-bearing distribution."

"Just tell me how to do it," Chen Hao said, rolling up his sleeves.

The two first moved the surrounding shelves aside and then set up support beams around the metal plate. Nana used a robotic arm to insert a jack into the gap and slowly pushed it up. The steel plate creaked, as if something that hadn't been touched for a long time was finally being disturbed.

"Slow down, slow down!" Chen Hao said, supporting the beam. "If you push any harder, it'll crack!"

“The output pressure has dropped to forty percent.” Nana adjusted the parameters. “An observable opening is expected to form in thirty seconds.”

With a snap, a slit about forty centimeters wide was pried open in the steel plate. A gust of cold wind rose from below, carrying the smell of dust and sheet metal.

Chen Hao took out his headlamp and shone it inside. The space below was empty, revealing several rows of metal shelves piled high with cans. Most of the labels were blurry and some had fallen off, but overall they looked relatively intact.

"I've struck it rich," he said.

"Warning: Food stored for a long time may spoil." Nana pulled up her portable airtightness detector. "Batch sampling and analysis are required."

"I know I can't just eat anything." Chen Hao put on his mask. "Let's bring up a few to test the waters first."

They set up a temporary cleanup area and cordoned off the area with tarpaulins. Nana used a puncture needle to extract several gas samples from inside the cans. The test results showed that 60% of the cans had normal gas pressure and the microbial content was within acceptable limits, indicating that they were safe to eat after high-temperature processing.

"There's more food than I expected." Chen Hao sorted and took notes. "Beans, meat, vegetables, even fruit. I don't know the expiration date, but at least it's not stone."

“Categorize them as ‘ready to eat,’ ‘to be processed,’ and ‘discard.’” Nana updated the list simultaneously. “Handle with care during transport to prevent secondary damage.”

By noon, the two had moved the first batch of supplies into the kitchen refrigerator. Chen Hao grabbed a can of beans, heated them up, and wolfed them down while sitting in a chair.

"Why do you think these people sealed off the warehouse in the first place?" he asked, chewing on beans. "There was still so much food left."

“There are no relevant records,” Nana replied. “But judging from the way it was sealed, it must have been due to an emergency evacuation.”

"We were too busy running for our lives to remember to close the door," Chen Hao shook his head. "Maybe the top collapsed and people couldn't get out, so they had to hide down below."

"The speculation is reasonable."

After finishing his meal, Chen Hao wiped his mouth and crawled back underground. "I still have to finish cleaning up the rest; what if there are other treasures?"

This time he went deeper inside. Behind the innermost row of shelves, a piece of equipment about half a person's height stood against the wall. The casing was covered in dust, but it was clear that it was a diesel generator. There were markings on the fuel tank, and the remaining fuel hadn't frozen yet. The control panel had several buttons, one of which was an indicator light that reflected light faintly.

"Huh?" Chen Hao leaned closer to take a look. "This thing... is it still usable?"

Nana scanned the device. "The main structure is intact, the engine block has no cracks, and the battery terminals are below the oxidation threshold. If the filter is replaced and lubricant is added, the chance of repair is 73%."

"Seventy-three percent?" Chen Hao laughed. "That's much higher than my passing rate last time."

“This equipment is not part of the current energy system planning projects,” Nana said. “Should it be included in the maintenance list?”

"Of course!" Chen Hao patted the machine. "It's winter now, and every power outage means we'll be freezing. Having a backup plan is better than running barefoot."

Nana entered the information into the system and marked it as "Level 1 Priority for Backup Energy Project".

The cleanup continued in the afternoon. They packed the discarded canned goods into boxes for later recycling. Edible portions were categorized, labeled, and placed in the storage area. Chen Hao counted the contents as he worked and found that the stock was enough for the two of them to eat for more than six months.

"I won't have to worry about food every day anymore," he said.

“Food reserves have improved, but the nutritional structure is still unbalanced,” Nana cautioned. “There is a lack of fresh fruits and vegetables and sources of protein.”

"You still expect me to grow vegetables?" Chen Hao laughed. "I'm too lazy to even open a can lid now."

"We could try cultivating cold-resistant fungi," Nana said. "There are already relevant technical solutions."

"Let's talk about it when I'm not lazy anymore."

As the sun began to set, the cleanup work came to a temporary halt. Chen Hao sat in the control room, holding a half-finished warehouse floor plan. Nana stood beside him, the screen constantly updating data.

“We’ll continue tomorrow,” he said. “First, we’ll move the rest of the shelves out, then we’ll check if there’s any water seepage in the walls.”

“Agreed.” Nana nodded. “I also suggest a preliminary disassembly and inspection of the generator to confirm the condition of its internal components.”

"Okay." Chen Hao yawned. "But we have to agree that if you're going to take apart parts, don't use your brain. Otherwise, I'll be lonely talking to you and no one will answer."

"The servo motor and control system operate independently and do not affect the interactive functions."

"That's good." He squinted. "I don't want to wake up one day and find that you've become half a robot and your speech is muffled."

Nana didn't respond, but simply threw a new task list on the wall. The top line read: Underground warehouse cleanup progress - 41% complete.

As Chen Hao watched, his head began to nod, and he was about to fall asleep again.

Just then, Nana suddenly turned towards the storage room.

"Changes in airflow in the underground space have been detected."

Chen Hao opened his eyes. "What does that mean?"

"The air velocity inside the ventilation duct increased by 60 percent for 18 seconds." She repeated the scan. "The cause is currently unknown."

Chen Hao frowned. "Did we open the door too wide today, and the wind got in?"

“The opening area is less than five percent of the total ventilation volume.” Nana pulled up the model. “The external wind pressure did not fluctuate significantly.”

Both of them looked at the crack leading underground.

Chen Hao slowly stood up, supporting himself on the table.

The wind comes from below.