The blue light inside the insulated box flashed again, but this time no one looked up.

Chen Hao stared at the toes of his shoes. His left big toe, ripped and bleeding, peeked out from the crack, feeling a slight numbness as it rubbed against the slag-covered ground. He wiggled his toe to make sure it was still usable before slowly straightening up.

“It’s incredibly punctual,” he said. “More punctual than an alarm clock.”

Carl was winding the last piece of wire into the device's casing when he heard this, but he didn't stop. "The next time it flashes, that's when we'll make our move."

Susan crouched by the rock face, checking if the pliers' clips were loose. She'd already bent that thing twice; if it malfunctioned again, she'd have to break the crystal by hand. She tested the force, closed and reopened the pliers, her voice low: "I don't want to rely on luck to defuse a bomb."

Nana stood at the entrance of the passage, the detector pointed forward. The waveform on the screen fluctuated steadily, like a heartbeat. She pulled up the timeline and marked the next trough—in seventeen minutes, the energy field would briefly drop, making it the most suitable window of opportunity to proceed.

“Model confirmed,” she said. “The three control routes have been generated.”

Chen Hao turned his head: "Speak like a human being."

“The first node is in the middle rift valley, used to deflect some of the energy flow; the second node is located in the heat flow convergence zone, forming a buffer zone; the third node is near the core periphery, the location of the main crystal.” She raised her finger to the map projection, “We don’t need to rush to the end all at once, we can proceed step by step.”

"Steady and methodical?" Chen Hao grinned. "I like that phrase. It doesn't sound like suicide."

Carl put the modified time-delay device into his tool bag, but the zipper got stuck. He yanked it open and started over, casually stuffing in a spare battery. "The shield won't last long, at most two hours. If the power goes out in the middle and the pulse leaks, all four of us will be roasted alive."

“Then don’t let it break.” Susan put away the pliers and dusted off her gloves.

Chen Hao cracked his shoulder with a popping sound. He ignored it, walked to the front of the line, and glanced at the timer on his wrist. The red numbers ticked: 16:43, 16:42…

“Less than ten minutes left,” he said. “When it ‘inhales,’ we’ll slip inside.”

Nana nodded and deactivated half of the functional modules on her right arm. The movement was slower, but the system load decreased by twenty percent. She lowered the detection frequency to the lowest setting, keeping only navigation and communication enabled.

“I can go last,” she said, “so that I can cut off the signal immediately if there is any interference.”

"You go in the middle," Chen Hao waved his hand. "Susan and I will scout ahead, you and Carl will bring up the rear. If it really explodes, you can retreat. We two can just run forward."

"Can you run?" Susan asked.

“My shoes are worn out, but they’re light and easy.” He lifted his foot and swung it around. “Besides, fat people are more resistant to falls, so the landing is cushioned.”

No one laughed, but the atmosphere relaxed a little.

Carl slung his tool bag over his shoulder and checked the seal on the insulated box. The tape he'd used last time was brittle and the edges were peeling up. He pulled a piece of cooling metal sheet from a compartment in his backpack, then tore off a section of insulating tape and wrapped it around the box layer by layer. Finally, he used a piece of molten slag to press down the corners, wrapped it again, and patted it firmly.

"It's like a metal box now," he said.

"The uglier, the safer." Chen Hao reached out and took it, tossing it a couple of times. "It's a bit heavy, but I'm not afraid of leaks."

Susan folded the drawings from the sealed bag and stuffed them into her breast pocket. Spare batteries, pliers, and a cutting knife were all secured to her belt. She tugged at the shoulder strap to make sure it wouldn't wobble.

“Ready,” she said.

Nana performed a final calibration of the detector, and the frequency successfully matched the crystal resonance window. A green checkmark appeared on the screen.

"Completed simultaneously."

Chen Hao stood at the entrance of the passage, with three people standing quietly behind him. Ahead was a sloping metal corridor, the walls glowing a dark red, like scorched iron. The air was scalding, and breathing felt like being burned.

He glanced down at the timer: 15:07.

“Let’s go,” he said, “before it ‘breathes’ out.”

The four began to move forward.

Chen Hao led the team, his footsteps crunching on the debris. Susan followed closely behind, her hand on the handle of the pliers. Carl carried his toolbox, walking cautiously. Nana brought up the rear, the detector continuously emitting a soft beeping sound.

Ten minutes later, the temperature rose by five degrees.

Chen Hao wiped his face, the sweat that had just appeared was quickly evaporated. He took a breath and slowed down. "Twenty minutes per shift, I'll hold on for now."

“You’ve only been gone for ten minutes,” Susan said.

“But I’m fat,” he chuckled, panting. “I’m a huge energy consumer, so I have to use it sparingly.”

The passage narrowed, and cracks appeared in the ceiling, emanating a faint red light. Nana warned everyone to avoid the area on the left, where the radiation level was three times higher. Karl nearly tripped as he went around it, grabbing the wall for support; his glove immediately started smoking.

“Even the walls in this place seem to want to bite,” he said, shaking his gloves.

"Don't take it off," Nana said. "Just another half hour and we'll reach the first node."

They continued onward.

They stopped twice along the way. The first time was because the detectors alarmed; the ground ahead had collapsed, revealing a deep trench with swirling reddish air currents beneath. They detoured around to the right ridge, inching their way along the wall. The second time was because the insulation box was vibrating more intensely. Karl quickly checked the shielding and found a corner of tape had come loose, which he immediately repaired.

“It’s getting anxious,” he said.

“It’s not that it’s in a hurry,” Nana said, looking at the screen. “It’s that the rhythm inside has changed. The tidal cycle has shortened by two minutes.”

Chen Hao frowned: "Does that mean... we don't have much time left?"

"To be precise, our remaining window of safety is shrinking."

"Then hurry up," Susan urged. "The plan remains the same anyway, we just need to finish quickly so we can get out of here sooner."

They quickened their pace.

After walking for another twenty minutes, the terrain began to descend, and a metallic, rusty smell filled the air. Nana's detector indicated that they were only three hundred meters away from the first node.

“There’s a platform ahead,” she said. “The geological structure is stable and suitable for deployment.”

Chen Hao nodded: "We'll talk about it when we get there."

The moment the words were spoken, the insulated box suddenly shook.

Everyone stopped.

Carl immediately opened the outer layer to check; the tape was intact, and the metal plate was still in place. He breathed a sigh of relief: "False alarm."

“No.” Nana stared at the detector. “The external signal has strengthened. The fluctuation amplitude has increased by fifteen percent.”

"Is it ahead of schedule?" Susan asked.

“No, the intensity has changed.” Nana pulled up the data for comparison. “The energy field is compressing, the range is shrinking, but the density is increasing.”

Chen Hao looked into the depths of the passage: "So, the things inside... are becoming more and more concentrated?"

"right."

"Shouldn't we also speed things up?"

“Yes, but the risk increases,” Carl said. “The device can only support two delayed triggers at most; any more and the circuitry will burn out.”

“Let’s do it all at once,” Chen Hao said. “We’ll set up the first node as usual, skip the second node, and go straight for the third node.”

“It’s too risky,” Susan objected. “There’s no buffer in between. If we fail, we won’t have a way out.”

“But time waits for no one.” Chen Hao stared at the timer. “If we delay any longer, we might not even have a chance to get in.”

Nana paused for a few seconds, then pulled up a new simulation path. "If we strengthen the shielding at the first node and extend the guidance time, we might be able to shift the energy flow for a longer period. This way, even if we skip the second node, we can still gain a twelve-minute window."

"Can you do it?" Carl asked.

“It needs to be adjusted on-site,” she said. “But I can do it.”

Chen Hao smiled and said, "Then it's settled. We'll reinforce the first node, and then go all out to attack the outer perimeter of the core."

The team set off again.

His steps quickened, and his breathing became heavier. Chen Hao's t-shirt was soaked through, clinging to his back like a hot towel. He didn't utter a sound, just kept moving forward step by step.

The 300 meters were covered quickly.

The platform appeared before us, larger than expected, with a flat ground and natural grooves in the rock walls, just right to hold the insulated box.

“This is it,” Nana said.

Carl put down his backpack and took out his tools. Susan checked the depth of the groove to make sure it wouldn't slip. Chen Hao stood by, watching them work.

"How long after the device is installed can it be started?" he asked.

“Five minutes to test it,” Carl said, unscrewing the casing. “Then we’ll wait for the next dip.”

Nana connected to the detector and began calibrating the trigger time. Susan spread out the spare materials for easy access. Chen Hao squatted down and touched the insulated box.

The box is still shaking.

He suddenly said, "Do you think it might... actually know we're coming?"