"The operating center?"

The brother and sister looked completely bewildered.

They exchanged glances, seemingly conveying some message to each other. Sun Muchen was taken aback, then shook his head repeatedly as if suddenly realizing something.

Wang Lan's expression turned to one of disappointment and frustration. She rolled her eyes at her and then looked at Old Zhang.

What is the central nervous system?

Old Zhang: "..."

He just realized that the message conveyed in the eyes of the brother and sister must have been that Wang Lan was asking again, "You've read a lot of books..."

Old Zhang explained, "These gear sets should be the mechanical components that control the overall operation of the final fortress. The wind, rain, thunder, lightning, moonrise and sunset, day and night in the residential area, as well as the defense mechanism of the final fortress, should all originate from here. However, these gears should only be a part; there must be other components that make up the overall operation of the fortress."

"Oh..." Wang Lan didn't understand at all. He waited for Lao Zhang to finish speaking before replying, "Let's walk forward and see if we can find anything else."

Old Zhang nodded, then patted Sun Muchen on the shoulder and said, "Don't be so nervous. The gears here are very noisy, and the lighting is poor. Even if someone is there, they might not be able to spot us. We just need to be careful and relax."

After careful consideration, Wang Lan agreed with Lao Zhang's opinion.

So the three of them set off with Wang Lan leading the charge. He held the Vajra Umbrella in one hand and a gun in the other, so that he could block bullets while launching a timely counterattack.

Old Zhang was in second place, since he was the only one relatively familiar with the environment and needed to communicate with Wang Lan about the route.

Sun Muchen walked at the back, which was naturally a way to protect her. With Wang Lan and Lao Zhang as two shields, she would be much safer. At the same time, if any problems arose, Sun Muchen could react quickly and retaliate in time.

The three of them continued walking forward, with the enormous gears slowly turning above their heads, emitting a crisp "clattering" sound. Under the fear brought by this behemoth, their hearts pounded rapidly, and they unconsciously felt an unprecedented sense of oppression, so they tacitly quickened their pace.

But the further they went, the more gears there were, and the denser they became. The group had to crawl and carefully turn sideways, making it increasingly difficult to walk.

As the gears turned, the eerie blue light gradually increased, falling on the serious faces of everyone. They saw dried bloodstains on the gears and bits of flesh ground to dust. Amid the noisy and roaring mechanical sounds, there also seemed to be a "sizzling" sound.

It sounded like it was being constantly squeezed, emitting a shrill scream that never stopped.

The surrounding temperature was noticeably rising.

Sweat quickly appeared on their foreheads.

The dimness that greeted the eye added to the hazy atmosphere, the air became humid, as if you could scoop up a pool of water with a wave of your hand, and breathing began to feel difficult and uneasy.

Wang Lan turned to look at the two people behind her. Seeing that their faces were flushed, even in the dim light, she took off her clothes, tore them in half, and handed them to the two people, saying, "It's too humid here, cover your noses and mouths."

The two took the clothes, nodding as they covered their faces. Although this made breathing a little difficult, the clothes blocked the moisture, making them feel much better.

Wang Lan continued walking ahead. He saw a gear directly in front of him, behind which seemed to be nothing but a hazy mist. He quickened his pace and passed through it.

The gears are gone.

Instead, there were thick metal pipes on the ground, spaced far apart, leading upwards. When Wang Lan looked up, he saw huge pistons in operation. Each movement produced a loud "whoosh" sound, and steam shot out from the top of the pistons, then merged into a misty fog.

Above the piston, countless sawtooth gears were constantly operating, and a huge metal chain followed the rotation of the gears, making a rhythmic clattering sound.

Water droplets condensed on the black pipe, one end connected to the piston wall and the other leading to a place that could not be seen ahead.

When the group approached, they found the ground to be extremely slippery, making it difficult to maintain their balance. They had to slow down, but the deeper they went, the more piston machines they encountered, and the louder the roar became. The vibrations they felt were even more pronounced, making them feel quite uncomfortable.

Then…

They found a body.

However, the corpse appeared to have been dead for a long time. In this damp environment, the flesh had rotted and turned white, and the entire body was larger than before, making it impossible to tell whether the corpse belonged to a human or an infected person.

Wang Lan and the others frowned, walked around the corpse, and continued forward.

More and more corpses came into view, all of them rotten beyond recognition. The more they looked, the more nauseous they felt, but there was no way to retreat now, so they had no choice but to grit their teeth and continue.

Amidst the booming sounds, a series of piercing hissing noises gradually emerged—sounds they had never heard before. The blue light reappeared in the misty vapor, and faintly visible, from the center of the blue light, was a hint of fiery red.

The group exchanged glances and cautiously quickened their pace.

The surrounding temperature dropped.

The water vapor gradually became thinner.

The gaps between the pistons widened, the blue light turned into a halo, a dense vibration came from beneath our feet, and the fiery red light in the center became like sunlight.

Wang Lan walked ahead, and he subconsciously felt an indescribable sense of oppression. So he took out the Vajra Umbrella, greeted the two of them, and rushed over first.

The dampness vanished instantly, and as his vision cleared, Wang Lan felt all the moisture and sweat on his body disappear. Bright light shone into his eyes, so bright that he immediately closed them. After a few moments of relief, he dared to open them little by little.

Before him appeared a massive fireball, floating in mid-air, its flames raging fiercely. Two blue, lightning-like beams of light swirled and swirled around the fireball, while four metal supports, like arms, extended from the four corners of the ground, pointing towards it.

From the blue beam of light, a continuous stream of iridescent light flowed toward the metal support, then rose upwards along the nearly one-meter-diameter transparent pillar.

Above the fireball, there seemed to be countless transparent jars of various sizes, with sparks and tiny blue lightning flashing intermittently within them.

Sun Muchen and Lao Zhang then walked over.

When Sun Muchen saw the giant fireball floating in mid-air, he was stunned and speechless.

Old Zhang frowned and said, "This...this is the power of the sun!"

The brother and sister were taken aback.

Old Zhang added, "If the mechanical units we see control the operation of the final fortress, then this reactor simulating the burning of the sun is the energy source of the final fortress!"