So the question is, the other party has been gone for at least half an hour, how can we catch up with them?

Du Yuqi was confident about this. He was not the kind of person who could only raise questions but not solve them. He half-knelt beside him, took out a clean white porcelain plate, and sprinkled some black crumbs on it. He said:

"I found these black crumbs on the carpet, and they were found here. You can notice that if that guy had been sitting here eating a few moments ago, this is where he put his feet. So it is very likely that they were shaken off from the soles of his shoes."

Crowds began to gather around and pay attention to these black fragments, which looked like dried asphalt residue, with a strange and oily luster on the surface, and also emitting some peculiar smell. Even the most knowledgeable people had never seen such a thing before.

At this time, Du Yuqi hadn't spoken yet. The captain of the guards who had been silent all the time came forward and looked at him carefully for a while, then said with some doubt:

"It seems that I have seen this thing before. When we searched the opera house before, we saw some leftover dirt in the warehouse near the stables. It seemed to be different, but the smell was almost the same."

Du Yuqi's eyes lit up, and he stood up and said:

"Where is it? Take me there quickly?"

Soon, the captain of the guard led them to the vicinity of the stable, and sure enough, they saw that something seemed to have been knocked over at the door of a warehouse. There was a black greasy stain as big as a pot lid, which looked like dissolved asphalt or sludge in the gutter, and there were several blurry footprints left by it.

This kind of thing would have been easily overlooked. If Du Yuqi hadn't caught this detail and mentioned it, there would have been a 100% chance that no one would have told him.

Seeing the black greasy stain, the others breathed a sigh of relief. Since there was such an obvious smell, it should not be too difficult to track it. However, Du Yuqi stared at this thing and fell into deep thought, as if there was some mystery hidden in it.

At this time, others were also very impressed with Du Yuqi, and they couldn't help but look at Du Yuqi and say:

"How did you notice this? The black residue on the carpet is not noticeable at all. At first glance, it looks no different from coal slag, right? And you actually found it!"

Du Yuqi frowned slightly, as if thinking about something, then shook his head and said:

"The reason why I noticed this thing is very simple, because this thing is very special, I have come into contact with it before and even got the real thing."

As he spoke, he took out two boxes from the dimensional ring. Both boxes were heavy and looked as if they were made of lead. Du Yuqi first chose the smaller lead box. After opening it, he found a black lump the size of an egg inside. It looked like a lump of coal with small stones embedded in it, and there was a slight crystallization phenomenon. This thing also gave off a peculiar faint odor, exactly the same smell as the oil stain on the ground.

Du Yuqi pointed at this thing and said:

"Since I entered the Arad continent, I have been dealing with mysterious organizations. I found this item in the Dark Curse Cat Demon settlement near Huttonmar. The Dark Curse Cat Demons there are accustomed to living on the abandoned crater platform, using the heat energy of the hot springs to hatch their cubs. They call that place Mud Navel Island."

"The mysterious organization placed a source of pollution in the cub gathering pool on Mud Navel Island, polluting the water source there, causing the cubs to die and the dark curse cat demon living there to go crazy. This is the source of pollution I found on Mud Navel Island."

After hearing what Du Yuqi said, both Mingxi and Duize were surprised and said:

"Ah? So this is the reason why the Cursed Cat Demon went crazy?"

Du Yuqi nodded:

"Yes, I went back and carefully studied the pollution source, but I still had no clue. Thanks to Tolin, I once again found some clues related to it."

Hearing Du Yuqi say this, Lin was a little surprised and said:

"Thanks to me?"

Du Yuqi nodded and smiled:

"Yes, do you remember the first time we met?"

Lin groaned:

"Was it that time on the mountain road of Xu Zu?"

Du Yuqi said:

"Yes, that was also the first time I met Xi and Meimei. We were still on the enemy side. Lin, you finally succeeded in burning the goods transported by the Xuzu Anti-Demon Group."

After hearing Du Yuqi say this, both he and Xi looked a little unnatural, while Lin just laughed and said:

"I just took advantage of the situation."

Du Yuqi narrowed his eyes slightly and said:

"If you hadn't successfully burned the cargo transported by the Xuzu Anti-Demon Group, I really wouldn't have been able to discover the problem with this batch of cargo! Look, the second box contains some samples I got from the escorted cargo that wasn't burned."

Everyone immediately looked towards the second box and found a mass of black, greasy, sticky semi-solid substance. This stuff looked somewhat similar to the pool of oil that had leaked on the ground, except that the stuff on the ground looked thinner, as if a lot of water had been added to it, while the stuff in the first box looked like a highly condensed lump of the black oil in the second box.

Obviously, the pollution source that Du Yuqi took out, the goods transported by the Xuzu Anti-Demon Group, and the black oil left behind by the mysterious organization should all belong to the same category of products. It can even be said with almost certainty that it is a special product from the mysterious organization, and there is no other like it!

After hearing what Du Yuqi said, Changmei and Xi's expressions suddenly changed, because they both thought of a very serious problem at the same time, and couldn't help but say:

"Then, if you put it that way, then didn't the Xuzu Anti-Demon Group help the mysterious organization before?"

Du Yuqi nodded and said:

"That's right. And according to my guess, the Xuzu Anti-Demon Group was hunted down and silenced before. It might have a lot to do with the goods they received this time. The other party knew that the goods were destroyed and might leak the secret, so they took the initiative to leak the news... Moreover, according to the style of the mysterious organization, even if the goods are successfully delivered, they will probably kill them."

"So what exactly is this thing?" Mingxi's words expressed what everyone was thinking.

Du Yuqi stared at the three samples in front of him, a sneer appeared on the corner of his mouth, and he shook his head slightly:

"It has a very strong polluting effect, but it also looks similar to fuel... Although I have some guesses in my mind, I lack sufficient evidence, so I can't make a definitive statement. But we can ask. Others may not know, but don't the people who transported the black oil know?"

After hearing what Du Yuqi said, everyone became alert. The smell of this strange black oil was very unique and pungent. It was already early in the morning and there were a large number of breath samples here. It would be very easy to track it, because Xiatli was close to the Stone Snow Region, and there were many creatures that were good at tracking.

Because in order to survive in the snowy area, finding food in time is an essential instinct. When everything is covered under the snow, an extremely sensitive sense of smell becomes the most basic prerequisite for survival. Only by finding prey can you survive. If you can't find it, you will be eliminated directly.

In this situation, hunting dogs and the like should all stand aside. The most common tracking creature is called snow shrews. These mice look like porcupines, and the hair on their bodies condenses into sharp ice spikes in winter. They usually retract the smooth blue and white ice spikes, and their bodies become shuttle-shaped. They can move very fast under the snow. Once they encounter an enemy, they will inflate the ice spikes on their bodies like an umbrella to protect themselves, making it impossible for the enemy to bite them.

The diet of snow shrews covers a wide range, including plants, meat, carrion, feces... As long as it is organic, it can eat it. Its sense of smell is even more terrifying. It can smell blood from ten kilometers away! Its sensitivity is seventeen times that of a hound!

However, this thing is difficult to tame, and only the Bantu animal trainers can use secret techniques to successfully make it obedient. However, there are not too many Bantu people in Shatli, so it is not difficult to find a few tamed snow hamsters at this time.

…

Soon, everyone continued to move forward under the leadership of three trained snow hamsters. After walking in the darkness for about forty minutes, they suddenly heard a scream in front of them, followed by a series of explosions and gunfire.

After noticing a fierce battle ahead, all the people dispersed. Those who could come to make a living were definitely not ordinary people, so they were as smart as rabbits. Du Yuqi immediately dodged to the side, and then quickly climbed to a higher place. The intention of doing this was obvious, naturally, he wanted to be above others and grasp the overall situation.

Just over a hundred meters ahead, there was a crossroads. An obvious temporary fortress had been built in the middle of the crossroads. There were also barricades around it to prevent forced collisions, and steel parapets welded with extremely crude techniques.

There is also a radar-like device above the temporary fortress, which is constantly rotating, but the coverage area is obviously much smaller. It should be used to detect biological activities within a few hundred meters around. The vanguard of Du Yuqi and his team should have been discovered by this thing. Now the fighting in the front is in full swing, and explosions are ringing one after another.

Just when Du Yuqi wanted to join the battle, his brows suddenly frowned, because he felt a strange, faint "buzzing, buzzing" sound coming from his ears. If it was the first time he heard this sound, he would definitely be very surprised, because although the sound was faint, it was so dull that his chest seemed to be trembling in resonance.

However, this was not the first time Du Yuqi heard this voice!!

When he first entered the continent of Arad, after he severely injured the clown, he heard this buzzing sound in his ears. Then, a huge steel fortress appeared and descended to rescue the clown. How could Du Yuqi not remember this sound forever?

"I really caught you!"

At this time, Du Yuqi took a deep breath to suppress his restless mood, and then continued to climb higher and tried to see higher places. As the saying goes, if you want to see farther, you must climb to a higher level, which is a true reflection of his mood at this time.

When Du Yuqi reached a higher place, the obstacles that blocked his view were thrown below him, and his vision immediately became wider. As expected, he found that behind the temporary fortress at the intersection was another square in the city of Shatli. This square was brightly lit, and the stars dotted around it outlined a huge outline.

Suddenly, these lights intertwined to form a giant object that looked like a huge city. It could be vaguely seen even in the darkness. This giant object was composed of various steel components. It could be seen that this steel giant also had several open gates, and all kinds of people and vehicles were flowing through it. It was obviously handling large quantities of goods.