Normally, at such a deep underground, the temperature is basically constant, and there are only two possibilities for this to happen now.

First: the passage is not parallel, but has a huge angle of inclination, either up or down.

Second: There is some unknown reason that is affecting the temperature here.

The first point Lin Congfeng didn't agree with, he believed in his feelings very much.

This passage is never too steep, if not parallel, at an angle of inclination.

At a small angle, a distance of more than a thousand meters is unlikely to cause very significant temperature fluctuations.

Then it must be the second possibility, but what exactly is the second possibility? Lin Congfeng felt that the answer was at the end of the passage.

At this moment, in front of him, a round iron door appeared in his field of vision.

Lin Congfeng was stunned, he didn't understand why there was a door here, and it was such a heavy door.

The iron door opens at a very small angle, from which it can be seen that the iron door is at least twenty-five centimeters thick.

This thickness was exaggerated so much that Lin Congfeng's mouth opened wide. What the hell is inside, it needs to be fitted with a door like this.

On the iron door, a strange pattern is painted in black paint.

This pattern does not actually exist, it belongs to a symbol in the family's internal ciphertext system.

This also confirms from the side that the project here belongs to the handiwork of the family.

Lin Congfeng only learned a little and a half of this course, but he was particularly impressed by this symbol.

On the cover of the book there are seven symbols, and this is one of them, which represents extreme danger.

Lin Congfeng's breathing was heavy, this symbol could never have been scribbled here.

The family would not do such a boring and unprofessional thing, and no one else would be able to draw such a symbol.

This meant that there must be something extremely dangerous behind this door, or something special that he didn't know about.

Lin Congfeng didn't know what he was thinking at this time, he didn't seem to be able to control his legs, and squeezed in towards the gap in the iron door.

The gap is so small that it is too narrow even for a child.

Lin Congfeng tried sideways several times without success, and in the end he had to take off his coat to successfully enter inside.

The coat was neatly folded by Lin Congfeng and thrown into the iron gate first.

Almost all the other equipment I carried with me was on my body, and those that I couldn't really bring were thrown into the iron gate.

He didn't know what was going on inside, and bringing every piece of gear was a necessary choice.

After Lin Congfeng entered the gate, he immediately pulled out his dagger and held it across his chest, making a standard defensive posture.

There was no movement, the only feeling was that it was cold here, and it seemed that this was the reason for the previous drop in temperature.

Lin Congfeng raised the fire fold in his hand, the area illuminated by the firelight was too limited, and he didn't see anything.

In desperation, he turned on the copper flashlight hanging on his body.

At the moment when the flashlight lit up, Lin Congfeng exclaimed, threw away the dagger in his hand and fell to the ground.

Because under the illumination of the flashlight, Lin Congfeng saw a coffin in front of him.

It must be a coffin, for the people of the Lin family, understanding the coffin is like understanding oneself, which is the most basic course.

In fact, Lin Congfeng was not afraid of coffins, he had seen all kinds of coffins countless times.

But in this environment, he suddenly found that a coffin appeared in front of him.

As a child, his reaction just now was not exaggerated.