The two double-mounted Maxim machine guns have been installed, and the door looks thicker and more solid after being upgraded.

In particular, the structure of the door has changed from a push-pull to a lift-up type. The entire door has been completely embedded in the wall. If you want to open it without lowering the door, you can only blow it up with the entire wall.

The doors originally made of reinforced concrete wrapped with ordinary steel plates have also been upgraded to solid heat-treated homogeneous nickel-chromium alloy steel plates with a thickness of 30cm.

During World War II, Japan used this material of steel as the main armor of Yamato-class battleships and stacked its thickness to the crazy 650mm.

In that era, the Yamato-class main gun armor was as thick as 650mm, which was impossible for any artillery to penetrate it in the immune zone.

In fact, the Federation found a piece of such steel plate after the war. In order to test the performance of this steel plate, they used the 410 main gun of the Missouri-class battleship to carry out zero-angle shelling at a distance of 300 meters before breaking through such a piece of steel plate.

But it was almost a century ago technology. Now nickel-complex steel has become an ordinary steel that can be bought in the steel market at will, and it is cheap.

The materials Chen Xin collected before were filled with such a batch of nickel-complex steel columns, which were sold as raw materials for metal processing.

In Chen Xin's original plan, these materials were used to reinforce the door, but also to reinforce the structure inside the shelter.

Of course, in Chen Xin's original plan, he did not plan to turn the door into a solid metal door 30cm thick, and use a few centimeters of steel plate to make a hollow structure, and it is enough that it is still reinforced concrete inside.

But after Ding Ning gave him the note, the inexplicable sense of crisis made Chen Xin choose to turn the door into solid metal, although this almost doubled the survival points he spent on upgrading.

Although Chen Xin’s gate is not as exaggerated as the main gun armor of the Yamato-class battleship, his enemies also do not have the main gun of the battleship.

As for the use of explosives, it cannot affect such thick armor, otherwise there would be no need to use armor-piercing bombs in war to effectively penetrate the armor of battleships.

Looking at the door that he could only describe as extremely strong, Chen Xin couldn't help scratching his head while feeling extremely at ease. Now the door has enough defense, but the walls are not as strong as the door.

However, there is no need to worry too much about this issue. After all, his shelter is underground, with a mountain above his head more than 200 meters high. The hardness of the thick soil layer will not be much worse than that of the metal after freezing. If you want to dig the frozen soil layer, it will definitely be impossible to rely on manpower.

So now, as long as Chen Xin doesn't open the door, no one can enter his shelter.

The hydraulic lifting structure of the door ensures the reliability of the door, but if it is out of power, it will be a bit twitching to open the door.

Fortunately, the hydraulic mechanism of the door lifting column has an emergency door opening device. If necessary, the liquid inside can be directly released, so that the lifting column can fall down instantly and open the door.

But this is an emergency measure that can only be used once, and can only be used at the most critical moment or when necessary, because once you do so, it will be difficult to close the door if you open.

With such a solid and reliable gate and Maxim installed on the gate as a defensive weapon, Chen Xin was completely relieved of his safety.

Back inside the shelter and sitting on the sofa in the living room, Chen Xin had enough room to think about the whole thing.

First of all, the beginning of the incident should be the attack on the No. 2 refuge in Baling County, which is the mission in which Qin Lan was injured.

Because the terrorists who attacked the shelter used suicide attacks in this incident, causing more than 20 casualties, which attracted the attention of the city government and set up an investigation team to conduct the investigation. The first investigation encountered by Chen Xin was also at that time.

Subsequently, the provincial government, who received the notice from the city government, was also shocked by this incident, so a special investigation team was sent from the provincial capital Xingcheng to the city, and formed a joint investigation team with the city's investigation team, and then conducted a second investigation.

According to Qin Lan, it is very likely that the city government grasped important clues during the first investigation and determined that the terrorists who caused the attack were in the area where the Chen Xin family was located, so the second investigation still included the Chen Xin family.

But there is a suspicion among them, because Qin Lan was injured, Ding Ning was sent to take care of her, and the two were given a month off. This happened after the attack and before the city government set up an investigation team for investigation.

"Uncle Ding and the Special Police Team knew in advance that this matter had something to do with me?" Chen Xin stroked his chin, and always felt something was wrong here.

Logically speaking, even if Uncle Ding wants Ding Ning and Qin Lan to protect him, he should have made such a decision after the first investigation and determined that the terrorists were in their area.

But Uncle Ding gave Qin Lan and Ding Ning a month off at the beginning, as if he knew what would happen in advance, and then he deliberately found a reason to send Ding Ning and Qin Lan away.

As for the note Ding Ning gave him before, Chen Xin thought it was normal for this note to come. After all, this is the second investigation and it is over. If any action is to be arranged, there should be enough clues and information.

However, Uncle Ding has always loved Ding Ning. In order to prevent Ding Ning from being in danger, he simply gave her a holiday before the disaster came and asked her to go to Mo Qingyan's place...

When Chen Xin thought of the holiday, he immediately got inspiration and connected several things.

Before the attack, as the captain of the special police force, Uncle Ding may have received information or clues from certain channels, but he did not know the time and place of the attack, or he did not know that the attack would cause such a large number of casualties.

So at this time, whether it is Ding Ning or Qin Lan, they all go to work as usual.

As the attack occurred, Qin Lan was injured, and more than 20 police officers from the SWAT team and the armed police were either injured or sacrificed, and things suddenly became worse.

Therefore, at this time, Uncle Ding sent Ding Ning to take care of her on the grounds that Qin Lan was injured, and directly gave them a month off, probably in order to keep them in a relatively safe place in the hospital.

This is why Ding Ning did not give him the note at the beginning, nor did he say anything to move over to Qin Lan for a while.

But as the two investigations unfolded, it was obvious that something that Chen Xin didn't know about was happening in the middle, which caused the things to change.

Ding Ning's notes were handed over to himself at this stage, and it was obvious that Uncle Ding's original arrangement had changed.

This may be a sign of what major action the joint investigation team is going to carry out, otherwise Uncle Ding would not have put his daughter here, and this may be in a shelter within the scope of terrorist activities.

But this is not necessarily the case. Chen Xin tapped his knees with his fingers. After straightening things out, his thinking became much clearer, and he also made new judgments.

What he analyzed just now was the idea of ​​the police and the joint investigation team, but if he put his perspective into this group of terrorists, Chen Xin felt that they might not come to his shelter.

Because although terrorists are crazy, they are not crazy. Since they can attack official shelters at the cost of more than a dozen lives and create suicide attacks, they must have their own goals.

No matter what the target is, suicide attacks are likely to be just the beginning, because for terrorist organizations, more than a dozen people who have been strictly trained to launch suicide attacks are also very valuable and cannot be wasted just inadvertently.

So the first attack they made was probably to attract the attention of the police and the city.

So assuming that their goal is achieved, the city government and the police's sight has been attracted to Baling County, which means that the city government and the police's attention to the city has decreased. In this case, if a terrorist wants to launch the next attack, where would he choose?

Chen Xin felt that the answer was already very obvious.

Thinking of this, he couldn't help but worry about his friends in the city, especially Mo Qingyan and Mo Qingxin. They lacked strong enough defenses and had no resistance. If something really happened, they really had no ability to deal with it.

Why don’t they come to me for a while?

Chen Xin considered this idea, but hesitated a little.

On the one hand, the Mo sisters may not be willing to come. On the other hand, if he wants to live in five people, four of them are girls, it will become very embarrassing for him.

However, considering the possible dangers, Chen Xin felt that he would wait until Qin Lan and Ding Ning came and discuss with them before making a decision.

Just like this, where to live...

Chen Xin couldn't help scratching his head. He finally upgraded the bedroom, but did he still have to sleep on the sofa?

But this is all a story later. Now Chen Xin feels that he should prepare for Ding Ning and Qin Lan to come and live. After all, they are two girls, so some things need to be prepared.

This inevitably made Chen Xin feel troublesome, but the arrival of Ding Ning and Qin Lan cannot be said to be unhealthy. At least these are two people who can work. Although they are just temporarily staying, they can help them share a lot of things in the shelter.

At least there are people who are helping with many things in the planting greenhouse, so Chen Xin doesn’t have to be busy from morning to late anymore.

Moreover, there are other people in the shelter, which can be much more lively. Some people chat with them and can play games together during the evening break.

To be honest, it is also good to play games alone, but it is happier to play with someone.

Thinking of this, Chen Xin couldn't help but look forward to the arrival of Qin Lan and Ding Ning.
Chapter completed!