Tian Xu rose from the air to an altitude of nearly 10,000 meters, further expanding the scope of the scan. Now his olfactory imaging can cover a range of hundreds of kilometers, and it is not impossible to further expand the observation range, but it needs to be at the cost of reducing the accuracy of the scan. At the same time, olfactory imaging uses the sense of smell as the basis of perception, and the diffusion of odor takes time, and when its detection range is expanded to a certain extent, there will be a serious lag phenomenon.

This lag has both disadvantages and unique advantages. Although the information lag will affect his grasp of real-time information, it adds a temporal characteristic to his detection, which can "see" what happened in the past, just like a photograph, so that he can also sniff out what has happened in the past.

When Tian Xu rose into the air, the olfactory imaging sent many things that had happened in the city in a few days to his mind. He "saw" the process of the invasion of the Demon Gate, the process of the evacuation of the residents, the ruthless slaughter of human beings by the Demon Gate, and the protection of the people by the military and police forces, which are also ordinary people, and the powerless but tenacious resistance of a large number of ordinary people in the face of the Demon Gate. Most importantly, he "saw" the way of the Demon Gate's invasion and the order of the selection of attack targets.

Tian Xu noticed that the first to be attacked by low-realm demonic beasts and demonic cultivators were the ordinary people in those places where people gathered, and their purpose was self-evident, it should be to cause panic and create conditions for their further attacks.

And the first to be attacked by the Demon Gate with a higher realm were some cultivators and supernatural people who originally lived in this city, and the purpose of this kind of attack was also easy to understand, cultivators were the main targets of the Demon Gate, and attacking cultivators was to weaken the overall strength of the earth's cultivation world. Thinking of this, Tian Xu couldn't help but think that the first wave of attacks launched by the low-realm demonic beasts at the beginning should also have the purpose of luring cultivators to make a move, so that the subsequent powerhouses could concentrate their forces to eliminate cultivators. And that's exactly what the Demon Gate did.

However, Tian Xu still found a little abnormality, there used to be a large number of high-level demon cultivators flocking to the outskirts of the southwest of the city, there were not many people there, it was a special area, many scientific research institutions were there, and the goals of these demon cultivators were concentrated in one institution over there.

There was nothing special about the outside of the institution, just a small courtyard, and there was only a four-story building in the courtyard, and some garages and other supporting buildings, the building was a little dilapidated and looked very inconspicuous.

The most peculiar thing is that this institution does not have the special aura left by cultivators, only a few cultivators who were attracted by the Demon Gate have been here, but in the end, they were driven away by the demon cultivators surrounding here because they were outnumbered. As for the local cultivators from here, there is not even one in this institution, could it be that the Demon Gate has concentrated a huge force to attack this place in order to eliminate the local cultivators like other places in the city, or is there any scientific research results or important items in this institution that can arouse the interest of the Demon Gate and attract the attention of the Demon Gate?

Tian Xu was very curious, and after concentrating for a while, he saw the sign hanging outside the gate of this institution: Federal Institute of Space Mechanics. This name made Tian Xu a little stunned, as if he had an inexplicable concern. He looked at the place closely, and because of the distance, he only saw a huge structure underneath it, but he couldn't see the details. The inexplicable concern drew him towards the building nearly a hundred kilometers away, and at the same time mobilized all his senses to observe the institute more closely and what had happened here.

After the outbreak of the Demon Gate in the city, waves of high-level demon cultivators and demonic beasts rushed here from the city, and there were also high-realm demon cultivators who came ashore from the seaside, and they didn't enter the city at all, so they rushed here directly, which is obviously a key target of the Demon Gate, and it is the most important target in Seattle. He "saw" a lot of traces left by the Demon Cultivators at the peak of Ning Dan and the fourth- and fifth-level Demonic Beasts, and he could occasionally "see" some traces of scales and half-claws inadvertently left by the Holy Realm. It's just that the Saint Realm Earth Immortal is used to being invisible, and there are too few traces left, but he can be sure that there will not be too few Saint Realm Earth Immortals who have been here.

The courtyard is equipped with advanced high-tech automatic defense weapons, ranging from ordinary guns and thermal weapons to laser weapons, microwave weapons, and more. The entire courtyard had been ravaged by these weapons and the methods of attack by the Demon Gate, and it also revealed the solidity of the building, and the humble building still stood in the aftermath of these attacks, showing no signs of collapse.

In addition to the traces left by the Demon Gate and local cultivators, there are also some traces of ordinary people's activities here, there are not many traces of ordinary people, and most of them are a few days ago, with such a fierce battle, there should be no ordinary people who will come here again in the near future.

The last person to leave a trace was in the seemingly rudimentary porter, from where two security guards were supposed to enter the tunnel, and finally reached the underground part of the building. The other one who came here was a woman who came by car.

The last woman to arrive left a clear scent trail and was supposed to have gotten out of the car at the door. At the same time, a man once came out of the building, came to the door, and finally entered the building at the same time as the woman, probably to pick up the woman, and the two entered the underground parking lot of the building in the same car.

The aura of these two people gave Tian Xu an extremely intimate feeling, he couldn't tell where this feeling came from, it was like an extremely close relative. However, to his confusion, the smell revealed that these were two young Caucasians, completely devoid of yellow blood characteristics, and that he himself had no Caucasian friends who were particularly close.

Unconsciously, Tian Xu had increased his speed to the fastest. After upgrading to the peak of Ning Dan, his speed also increased significantly, and it only took ten minutes for him to arrive at this research institute located nearly a hundred kilometers away, and ponder the characteristics of this building on the periphery.

Upon reaching the building, the grand structure of the building set in the ground was revealed to his all-powerful spiritual realm. This small building, which has only four inconspicuous floors on the ground, has more than 30 floors underground, and it is 150 meters underground. Moreover, between 30 and 70 meters underground, there are also multi-layered three-defense structures, which are estimated to be able to resist the attacks of ordinary nuclear bombs or ground-penetrating bombs specially designed to deal with underground civil air defense fortifications. A little more than 100 meters underground, there is a small nuclear reactor, and judging by its structure, it may be used to provide energy for this building. As long as the reactor is not destroyed, the institute can remain in this underground structure for a long time, waiting for reinforcements to arrive. This shows the importance of this research.

Tian Xu's spiritual realm has now expanded to more than two hundred meters, and he can completely envelop this underground building, and he can also see the details of this building as it is, and this building is also completely undefended in front of him, he can directly step over that layer of defense measures through the teleportation ability in the field, and enter any position in this building.

Now there are nearly a hundred people stranded in this institute, most of these people are busy in different rooms, some are working nervously on the computer, some are doing some experiments, or observing something through specific equipment, obviously there is a special way to contact the outside world, and the people here seem to be completely unaffected by the outbreak of demonic beasts in the outside world.

On the twenty-sixth basement floor, he found the two people he cared about the most.

At this time, Kuzo and Firiel are in a hall on the twenty-sixth floor of the basement, there are only these two couples in the huge hall, Kuzo is boxing in the hall, in the eyes of Tian Xu, who has cultivated to the peak of the fourth layer, Kuzuo's boxing technique is nothing special, and the strength is not great, but between one move and one style, the air is pressed by the friction of the fist, making a hissing sound like a paper tear and a popping sound when the impact drill is working, and the compressed air forms layers of ripples, which are slowly released in the air. Some of the exercise facilities may have been affected by Kuzo's punching wind, and some have been staggered, and some have been shattered.

Fillel sat on a yoga mat not far away, smiling at her husband, completely oblivious to the punches that rushed in front of her, and when they reached her, they faded and faded, and by the time they reached her, they were already like a breeze blowing on her face, and could only barely blow her hair.

Tian Xu took a closer look at Kuzuo's realm and found that he should still be only in the state between the realm of Qi Gathering Dacheng and Ning Dan, but the power of his pair of fists should already be able to challenge the cultivators of the middle level of Ning Dan, and the strength of this person was not even below his original self.

The couple were quite young, Cuzo was obviously older than Fillel, and should only be about thirty years old, while Fillel, who was sitting next to him, looked only in her twenties, young and beautiful. It is not easy to reach such a state at such a young age.

After watching it for a while, the punch style of Nakuzo became weaker and weaker, and the sound became quieter and quieter, and the speed of his punch gradually slowed down, and finally stopped. He reached out and touched the corner of his forehead suspiciously, looking a little confused, it seemed that he had encountered difficulties in practicing boxing. He wandered back and forth a few times, and finally came to Fillel, sat down, closed his eyes, and fell into deep thought.