It was not an ordinary sewage treatment tank.

It was a special kind of equipment similar to a reaction vessel.

The thickness of the outer wall of each metal tank exceeded that of a main battle tank’s reaction armor.

During the operation, large amounts of chemicals and gene reagents had to be injected into the pool. That barely neutralized and diluted the experimental residue, monster feces, and various waste materials, enough for it to not cause serious damage to the environment or leave any traces behind.

The valves on top of several metal tanks were creaking and emitting hot scarlet steam.

It was hard for Meng Chao to imagine what kind of dangerous substances they were dealing with that required them to be so cautious as if they were facing a great enemy.

Even after more than ten processes, the sewage that was eventually discharged into the underground river still contained a large amount of Blood Flower spores, strong radiation, and heavy metal substances.

“D*mn it, are these audacious b*stards hiding here and injecting Blood Flower spores into the Apocalyptic Beasts’ blood vessels?” Meng Chao muttered to himself.

Apart from that, he also found traces of burning, tearing, and maintenance on several metal tanks.

The bases of several metal tanks had apparently been installed recently.

All the signs indicated that a small-scale explosion had occurred there.

The shock wave produced by the explosion was everywhere, leaving traces of it whistling past.

After pondering for a moment, Meng Chao felt that the small-scale earthquake not long ago had caused a serious malfunction in the sewage treatment system. The malfunction had escalated to a critical level, causing the explosion. Hence, a large amount of sewage flowed along the underground river to the surface.

“Strange. Judging from the style of the manipulator behind Horizon, he should be a very cautious person.

“If a sewage treatment system like this is damaged, it’s possible for a large amount of ‘evidence’ to flow out of his control. His style indicates that he would likely stop the experiment immediately and wait for the sewage treatment system to be completely repaired. He should also figure out the new tributaries of the underground river after the earthquake before he slowly starts work.

“Why? He knows that there’s a risk of exposure.

“Why does he still have to carry out high-intensity experiments day and night, releasing so much sewage that he ended up being discovered by Tailless Monkey?

“There’s only one possibility.

“This person can’t wait any longer.

“He has to produce the results of his experiments in the shortest time possible—the Blood Flower spores have to be used in real combat as a biological weapon!”

Beads of sweat appeared on Meng Chao’s forehead.

He could not wait to crawl into the reactor and follow the tubes all the way to the Blood Flower laboratory. It was hidden behind the sewage treatment system, deep within the layers of rocks.

However, that was impossiblebecause the sewage treatment system was filled with burly men armed with guns.

Their bodies were sturdy, like brown bears standing on their hind legs.

Their eyes were sharp, like that of hungry tigers and wolves.

They were patrolling the area silently. Even though they were wearing battle boots with steel plates embedded in them, they were as light and secretive as cheetahs when they walked.

The sewage treatment station, which was buried nearly a hundred meters underground, did not even allow a mosquito to fly in.

They had been on duty there for a year and a half, and certainly, no intruders would sneak in from the underground river. It was filled with super-strong radiation, as well as heavy pollutants, and it was inhabited by deformed monsters.

Nonetheless, their gaze on every corner of the cave was still as cautious and sharp as the first time they were on duty. They did not tire of their duty.

Meng Chao found that the guards’ gazes were like scythes that had been polished to the point of being shiny, sweeping past the tip of his nose.

If he had not broken through to the Deity Realm and cultivated the Walking Corpse technique that was especially used to conceal himself, Meng Chao felt that he would have been discovered.

The guards were all experts.

They had definitely killed before and seen blood. They had seen monsters clawing their organs from their chests and stomachs with their own eyes. Yet, they could snatch their organs back without batting an eyelid and stuff them back into their chests. Then, they would cover their stomachs and kill the monsters.

They were definitely different from those security guards who could only be considered passable on paper.

Meng Chao detected a total of eighteen guards.

Their patrol routes overlapped with each other, ensuring that each guard would appear in the field of vision of at least three companions at the same time.

No, it was not eighteen guards.

The last guard was very cunning, hiding in a specially dug hole above the cave wall.

The diameter of the hole was less than one meter.

Its surroundings were as smooth as a mirror and perpendicular to the ground. There was no rock wall to stand on.

The entrance of the cave was sealed tightly with an armor plate that was used specifically for anti-aircraft guns. Only small holes for observation and shooting were exposed.

There was a sniper.

Through the observation hole, he could see the movements of the other eighteen guards clearly.

Even if there was an intruder who could sneak up behind every guard like a ghost and cut their throats before they realized what was happening, the sniper would see everything.

Moreover, Meng Chao had no doubt that there was something strange about his hiding place. It was connected to some kind of alarm system. The changes in his physiological parameters were monitored to determine if there was a need for an automatic alarm.

After all, snipers were extremely calm. Most of the time, they could accurately control their physiological parameters.

If his breathing, heartbeat, blood pressure, and even the oxygen content in his blood changed drastically due to Meng Chao’s attack, the alarm would sound throughout the entire Blood Flower laboratory.

It was a scenario that Meng Chao did not want to see the most.

No, the well-trained guards were not the end of it.

Meng Chao also found a dense cluster of surveillance cameras, detectors, and information gathering devices around the cave, including inside and outside the sewage treatment system.

The density of these surveillance devices was like that of a minefield with mines planted repeatedly.

It was not necessarily used to guard against intruders.

It was mainly used to monitor the purification of sewage, the geological changes around the purification system, and to guard against the destruction of mutated creatures.

The vast majority of mutated creatures had relatively advanced intelligence and did not dare to offend this underground dragon’s den and tiger’s den.

However, under the Blood Flower spores’ modulation and stimulation, there would always be some bold and unusual creatures. They were like moths to a flame, seeking their own doom.

Now, the information gathering devices had become an impenetrable iron wall in front of Meng Chao.

Meng Chao closed his eyes and overlapped the patrol routes of every guard that he had just observed, as well as the monitoring range of every heat source surveillance probe and the information gathering devices. Right then, he was shocked to find a scarlet light in his field of vision representing “danger.”