The overhead light went out, but the crack continued to widen.

Chen Hao didn't move, his breath caught in his throat. He heard a metallic scraping sound coming from below, like rusty gears being forcibly turned. Then, a mechanical arm touched the edge of the ground, its joints gleaming with a dark red light.

"Stand against the wall!" he whispered. "Don't scatter!"

The four quickly moved towards the inner side of the curved passage, their backs pressed against the cold metal wall. Susan's hand had already reached for the pulse gun, Carl raised the vibrating saw in front of him, and Nana raised her wrist, casting a faint beam of red light to scan ahead.

“Three,” she said. “Spider-like structure, highly synchronized movement patterns, and the core energy source is located at the abdominal junction.”

Another mechanical limb climbed up, its claws scraping the ground with a piercing sound. They had no eyes; their heads were equipped with a ring of sensors that slowly rotated, as if detecting heat sources.

"Can they sense temperature?" Susan asked.

“More than that,” Nana said. “They locate their targets using energy pulses from underground, and the electrical equipment on our bodies is the signal source.”

"Then turn off the headlamps," Chen Hao ordered immediately. "Turn off everything that doesn't require electricity."

The helmet lights gradually went out, leaving only Nana's scanning red light still running. She turned her power down to the lowest setting, maintaining only basic detection functions.

The first mechanical monster began to move, crawling along the ceiling at a slow pace, but each step landed precisely on a support point. The second circled to the left, while the third approached them head-on.

“It’s flanking,” Carl whispered.

“It’s not an encirclement.” Nana stared at the data stream. “It’s a trap. The one in the middle deliberately exposed its position to force us to concentrate our firepower, and then the other two attacked from a blind spot.”

"Then don't hit it," Chen Hao said. "Wait for it to move."

A few seconds later, the one in the middle suddenly accelerated and charged forward, while the other two instantly sped up and attacked from above and the right side respectively.

"Let's do it!"

Susan raised her gun and fired. The electromagnetic blast struck the monster's side limb, sending sparks flying, but it only paused for a moment before continuing its advance. Carl swung his vibrating saw, the high-frequency vibrations numbing the air and forcing back the one on the right. Nana stepped to the front, her right arm raised to block, taking a claw strike head-on; the clanging of metal was ear-piercing.

"The core is below the abdomen!" she shouted. "We must destroy the joint connection points!"

Chen Hao pulled a flare from his backpack, pulled the fuse, and threw it deep into the tunnel. A blinding flash of light instantly disrupted the monsters' sensors, causing them to momentarily freeze in their tracks.

Right now.

Susan changed to a new magazine, aimed at the one that had just been hit, and fired a shot into its rotating joint below its abdomen. The joint shattered, its entire hind leg twisted and deformed, and the monster lost its balance, crashing headfirst into the wall.

"efficient!"

Taking advantage of the moment, Carl rushed forward, severed the other forelimb with a vibrating saw, and then kicked its support frame. The creature tumbled and crashed into the crack, got stuck at the edge with a snap, struggled a few times, and finally fell into the darkness.

The last one hesitated for a moment and stopped in mid-air.

“It’s receiving instructions,” Nana said. “The energy chain hasn’t broken yet.”

Before he could finish speaking, the monster suddenly swooped down and pounced on Chen Hao.

He had no time to dodge and could only raise his arm to block. In the nick of time, Nana rushed over and pushed him away, but she was sent flying and slammed her back against the wall. Her right arm guard dented, and tiny sparks flew from the joint.

"Are you alright?" Chen Hao helped her up.

“The outer casing is damaged, but it doesn’t affect movement.” She looked down to check the system status, “but another impact could cause a short circuit.”

The remaining one climbed back up to the top, seemingly waiting for something.

“It won’t attack alone anymore,” Nana analyzed. “Two of them were destroyed just now, and the energy feedback was interrupted. It is waiting for a new driving signal.”

"Then let's make the first move." Chen Hao looked at Susan, "Can we still fight?"

"The barrel is overheating and needs to cool down for two minutes."

“I’ll hold it off.” Carl gripped the vibrating saw tightly. “You guys find an opportunity.”

He took a few steps forward, deliberately revealing his position. The monster was indeed attracted and slowly approached along the ceiling. Just as it was about to pounce, Chen Hao suddenly activated the pulse transmitter function on his communicator, releasing a burst of noise signal.

The monster's sensors malfunctioned, causing a delay in its movements.

"Now!"

Susan raised her gun and fired a single, precise shot into its core. An explosion rang out, sending metal fragments flying. The creature twitched a few times, then fell from the wall, crashing into the previously broken support frame. With a deafening roar, a corner of the area collapsed, dust billowing everywhere.

Silence fell upon everything.

Chen Hao, panting, brushed the dust off his clothes. "Dead?"

"The energy reaction has disappeared," Nana confirmed. "We're safe for now."

Carl flexed his left arm and frowned. "I just got scratched, it hurts a bit."

"Let me see." Susan walked over and noticed a tear in his protective suit and a shallow cut on his skin. She took out some emergency medication, sprayed it on, and then sealed it with tape.

“No problem,” Carl said. “I can still walk.”

Nana began the self-check and repair process; the dent in her right arm slowly returned to its original state, but the scanning system required manual calibration. She squatted on the ground, her fingers rapidly swiping across the virtual interface.

“There are no active units within a radius of 30 meters,” she said. “But there is a faint energy accumulation point 10 meters ahead, which may be a residual signal source.”

"Go take a look," Chen Hao said. "Don't touch it, observe it first."

The group regrouped, maintaining a safe distance. They moved slowly along the left wall, cautiously testing the waters with each step.

Halfway there, Susan suddenly stopped. "Listen."

A faint humming sound came from afar, like the sound of a machine restarting.

“Not on the same frequency.” Nana looked up. “A new device is starting up.”

Chen Hao gazed into the darkness ahead. That area was deeper than before, and the red light of the symbols flickered, as if responding to some kind of call.

"Aren't we arguing too loudly?" he said. "We've woken up the whole family."

No one laughed.

They continued forward, their steps becoming even lighter.

As they approached the energy point, Nana gestured for them to stop. She crouched down and shone her flashlight on the ground. There was a metal plate there, its surface engraved with the same triangular patterns as the one in the main control room, and it was slightly warm.

“This is a node,” she said, “but it’s not the end.”

Chen Hao stared at the board. "Does that mean there's an even bigger one behind it?"

Logically speaking, this is just a branch.

Carl gripped the handle of his toolbox. "So we've only just walked in?"

Susan didn't say anything, she just checked the gun over.

Nana stood up, and the scanner restarted. Red light swept across the surrounding walls, revealing several hidden grooves that radiated outwards.

These grooves began to light up.