I can see experience bars after being transported to another world.

Regarding the reverse surge of energy.

For a moment, neither Lu Yuan nor Bo Lun had any good solutions.

For now, we can only observe.

The sixth night came quickly.

The light from the runes on the distant city wall dimmed a little more.

And tonight, the ghouls will attack again.

Fortunately, the number is not large.

Only a few individuals emerged from the direction of the burrow and crawled towards the position along the area covered by the fungus.

They were all ghouls in a state of absolute hunger, emaciated, with their ribs clearly visible, and their eyes filled with a thirst for flesh and blood.

Bol and his men easily resolved the issue.

A dozen or so.

It didn't take much effort.

But this was not a good start. After two consecutive nights of silence, things from the Abyss were resuming their probing attacks.

Although it was just a slight extension of its "tentacles" to check if the defenses here were still intact.

Lu Yuan stood at the second-floor window, watching Boer's men drag the ghoul remains onto the bronze surface and wait for them to corrode on their own.

Occasionally, sporadic gunfire could be heard from other positions in the distance, but it quickly subsided again.

Buren was on site, checking the gray-green backflow every two hours.

The grayish-green substance flowed steadily along the section of copper pipe he had repaired, maintaining its direction and concentration.

And there was almost no fluctuation.

Both the concentration and the flow rate are almost identical.

It felt like it was being precisely controlled by something.

Burren began to frown after the third test.

This shouldn't be the pattern of natural pollution backflow.

The things on the other side of the abyss are so chaotic; logically, they should be surging like the tides.

However, the contamination inside the copper pipe was far too uniform.

If it weren't for the fact that this section of the pipeline was repaired by chance this time...

Now Glock has entered the inner city with these two pieces of information, hoping to find some clues.

The horizon began to turn white.

Footsteps came from the side.

It's Buren.

"Come and see, this seems to be good news." Boren gestured for Lu Yuan to come over.

"Oh?"

Lu Yuan walked over and squatted down.

Beren's fingers were slowly sliding along the surface of the copper tube.

"When I was repairing this section of the pipeline yesterday, I only noticed the corrosion on the inner wall and that the copper plate had been touched."

He stopped pointing, his fingertip touching a tiny protrusion on the tube wall.

"But during monitoring last night, I discovered a problem."

He glanced at Lu Yuan.

"The pollution is too stable."

Lu Yuan frowned.

"We tested every two hours, and the results were almost identical six times," Beren said in a low voice.

"Have you ever seen anything like this? The underground pollution couldn't possibly be this evenly distributed, unless..."

"Unless the source isn't in that underground place, or something is controlling it."

"Yes." Burren nodded. "That's why I thought about it a bit more last night."

He tapped along the bump with his fingers.

"Then I thought, maybe I've made a mistake, maybe this piece of copper pipe is wrong."

Lu Yuan leaned closer to take a look.

Lu Yuan couldn't really make out anything from the yellowish-black bronze pipes.

"What's wrong?"

"These were all replaced later," Beren said in a low voice.

He drew two lines on the ground with his cane.

"The original transmission network of the city wall was laid together when the city was built. The bronze material and the style of the inscriptions are the same as those on the city wall, and every stroke was hand-carved."

He pointed to the copper pipes at his feet.

"But this pipe clearly doesn't fit."

He raised his head.

"Someone dismantled this section of the original structure and replaced it with one they cast themselves."

Lu Yuan's gaze darkened.

"Could it be for repairs? Or... what's the direction?"

Beren stood up and tapped the pipe wall with his cane.

"This is the second reason I called you here."

He squatted back down, placed his palm on the pipe wall, and slowly pushed it along the direction.

"I have studied the inscriptions of Bronze City carefully. Their direction is easy to guess, but this one is different."

His finger stopped at the bend in the pipe.

"It veered downwards, extending underground, not connecting to the outer city, but heading in some underground direction."

Lu Yuan was taken aback.

"Where do you think this pipe leads?"

Buren paused for two seconds, then stood up and dusted off the rust from his hands.

"I don't know, but it definitely can't be that abyss underground."

He turned around and looked into the distance.

"Think about it, when we went down into the abyss last time, we saw bronze pillars that were the foundation level, and the inscriptions were even older than those on the city walls. Those things were definitely built along with this city."

"Berlen continued," he said.

"With that level of inscription and copper concentration, the sealed object would be absolutely catastrophic."

"Even if it's just overflowing, it's definitely not something a copper pipe of this thickness can withstand."

"unless..."

Lu Yuan understood what Bo Lun meant.

"Unless they didn't come directly from the abyss."

"Yes." Buren nodded.

"The end of this pipe is most likely not in the abyss, but somewhere underground, where there is a source of pollution."

He tapped the ground with his cane, then pulled out a roll of parchment from somewhere.

The general layout of the Bronze City is densely drawn on it.

Buren pointed to a spot above and continued.

"But if someone creates a new contamination point on the seal, such as in the underground pipe network of Bronze City, then no matter how strong the seal is, it will be useless."

"Underground pipe network layer?"

"Yes, there's a network of pipes underground in Bronze City, containing sewage, rainwater, refuge passages, storage rooms... it's all there."

"And I estimate that this pipe goes in the direction of the underground pipe network."

Buren remained silent for a few seconds.

"I'm going down to check it out. I'll follow this pipe and trace its path. Once I get there, I'll know exactly what's going on."

Lu Yuan glanced at him but didn't say anything.

After a slight hesitation, Buren added another sentence.

"I'm very interested in this kind of contamination that can pollute copper, and of course the Night's Watch can't just stand by and do nothing."

Upon hearing this, Lu Yuan finally nodded.

"Let's talk about it during the day."

"clear."

The night passed quickly. After confirming that there were no ghouls, Lu Yuan instructed Boer to arrange for some of the night watchmen to keep patrolling the collapsed area.

As for the rest of the people, they will come with me.

The target was 300 meters behind the collapsed position, behind a half-collapsed stone wall.

There are inspection ports for underground pipe networks there.

The cast iron cover plate, less than one meter in diameter, is embedded in a groove in the copper floor.

The cover was covered with a thick layer of saprophytic fungi, and the grayish-green fungal layer glued the iron cover and the surrounding copper plate together.

Upon seeing this, Lu Yuan felt a sense of foreboding.

Let Bohr sprinkle copper powder around the edge of the cover plate.

A hissing sound rang out, and the bacterial layer quickly curled up and fell off.

Kel used a copper crowbar to pry open the cover.

The rusted iron cap made a dull cracking sound, and a damp, cold wind carrying a strange stench rushed up from the cave entrance.

After some time, Lu Yuan finally looked at the vertical shaft.

The iron ladder is embedded in the well wall and extends downwards for four or five meters.

I just glanced down.

[Environmental Sensing: A small amount of pollution source detected...]

"By the way, have we informed the Alchemy Workshop about taking over the underground pipeline?" Lu Yuan turned to look at Bo'er.

"The notification has been given, and the personnel involved in this operation have also reported: myself, Captain Lu, Berenkel, and two other brothers."

Both of these brothers are veterans.

An old soldier with a stubble beard and missing half of his little finger on his left hand, and a nimble young man.

There were six people in total.

Two sandworm oil lamps and four jars of spare oil.

One jar of fire powder, two bottles of mithril, two jars of copper powder, and other items.

"Go, get off."

With Lu Yuan's command.

The crowd filed in.

The shaft is not deep.

It only took a little over four meters to reach the bottom.

The soles of the boots made a dull thud as they stepped on the wet stone bricks.

The sandworm oil lamp was lit, and its bright white light spread out.

Before us was a passageway about two meters wide.

The walls are made of brick and stone on both sides, and the top is a copper arched frame.

Water seeps through the cracks in the stone bricks on the ground, accumulating into a shallow layer.

The air is damp and chilly, and your breath condenses into white mist.

The first thing Buren did was not to look at the road, but to touch the copper frame on the wall.

"The copper is still conducting electricity here! The situation doesn't seem so bad yet."

At this moment, Bor said:

"The underground pipe network is very safe. The city hall used to have people specifically responsible for its maintenance. Besides, quite a few people live here. And if I remember correctly, there should be a separate lighting system here..."

Bohr didn't continue, because as far as he could see, it was pitch black.

There was no sign of the so-called lighting system at all.

At that moment, Lu Yuan was holding up a lamp and looking to both sides.

Every three or four meters along the wall, there is an iron lamp holder, petal-shaped, with a fluorite or oil lamp placed in the center.

But at this moment it's all empty.

Some lamp holders are still embedded in the wall, with only the base remaining.

The upper half was broken off at the waist and lay askew to one side. The broken surfaces of the iron petals were jagged, showing signs of being forcibly broken.

The marks look very similar to the way the ghouls broke lampposts on the ground.

"It was the ghouls who did it," Bor said in a low voice.

Lu Yuan did not respond.

He was looking at something else.

On the left wall of the passage, about one meter above the ground, there is a dark red drag mark.

The drag marks extended from the front, drawing a crooked arc along the wall before disappearing into the shadows at the corner.

is blood.

Blood that has been there for a long time.

It has dried completely, turning into a dark red, almost black, thin film.

But the shape of the mark says it all.

"Walk."