In the blink of an eye, at midnight, Ryuko, Xu San, and Ozu each carried a bag of equipment and quietly dived from the villa to the mountain. After a day of noisy daytime, the ghosts didn't catch a single one, and they saw a yacht of unknown origin going away, they thought that the person who flew the drone had already been driven away, so the guards only strengthened the patrol around the island at sea, and they didn't think that the enemy had already sneaked into the villa area, let alone that someone would sneak out of the villa area at this time, so they went to the mountain quite easily.

The island is lonely in the deep sea, when the moon in the sky is faint and the stars are scarce, and the mountain is hazy and visible, and it is possible to walk at night without lighting, in fact, it is more conducive to the haunting of night walkers than the dark night when you can't see your fingers. If lighting is needed, even if you are careful, you can be spotted with fire. In this hazy sky, you can see people within one meter, and you can't see people three meters away, plus the role of night clothes, walking through the shadows of trees in the mountains, and it is excellent to hide your whereabouts.

Long Zi and Xu San both like this kind of night very much, especially Xu San, he is like a fish in water, the dragon returns to the sea, he takes the lead and walks extremely fast. It's only bitter Ozu, the youth of this stick country, Ryuko doesn't understand why he calls a woman's name, it seems that his physical fitness is good, but when he goes to the mountains to walk at night, he can't do it at all, and the arrogant stick always knows that he is such a frog at the bottom of the well when he sees the real chapter.

Xu San led Ryuko and Ozu to the cave in the middle of the mountain from memory.

"Judging from the environment outside the cave, there should be no one in or out of this cave, and no other animals should enter or leave, so there should be no mystery. Xu San said.

"Brother Xu, this is not necessarily, you look at the surroundings of this cave, there are no trees growing bare, there are not even weeds, but there is not even a grain of bird droppings, don't people think it's strange? Although there are not many islands on this island, there are many bats, and those bats must inhabit the mountains during the day, such a big hole is a natural bat nest, but why are there no bats in and out?" Long Zi disagreed with Xu San's point of view.

On this small island, on the pier to the west, there are more than a dozen species of island life, and in the woods to the east, there are a few mountain birds and many bats, but, according to the reason, this cave should be inhabited by bats.

"Not necessarily, you're busy this cave is eastward, normally speaking, eastward caves, bats don't like it. Xu San still insisted on his own point of view.

"Two seniors, we've all arrived, isn't there any mystery that will be clear when you touch it?" Ozu said.

"Yes, let's go into the hole. I'll take the lead, Ozu, you follow me, and Ryuko, you hold back. Xu San said.

"Okay, action. "Anyway, it's all here, and if you don't go in and see it, no one knows what's going to be inside.

The cave is not small, and behind the entrance is a wide hall that can accommodate dozens of people. The dragon carefully searched the cave for traces of human activity, but found no traces of human activity. There was no trace of human activity at all, and the dragon was even more suspicious.

This small island is a little bigger, this mountain is also a little bigger, this small island has a secret research base of ginseng pine, but the secret base built at such a large cost, every grass and tree on this mountain should have been in the hands of the security personnel, that is to say, this such a big cave, they should have been here a long time ago. But why is there no trace of human beings? Unless, artificially, someone doesn't want others to see that there has been human activity in this cave, which is called trying to cover the barrier.

"Ryuko, there is a discovery. At this time, Xu San's voice came from the walkie-talkie.

"Brother Xu, be careful. Long Zi didn't ask Xu San what he found, he just asked him to be careful.

"As you expected, there is monitoring equipment in front of you, and the installation is very hidden, and I almost fell for it. Xu San said.

Before entering the cave, Long Zi asked Xu San to have a scanner to scan whether there were electronic devices such as surveillance eavesdropping before moving forward, and now it seems that he really guessed correctly, this cave may be part of the underground base.

"Not good, fast back, it's an exhaust port. Xu San suddenly exclaimed again.

"Exhaust vent? You mean, the exhaust gas from the underground research base is discharged from here?" Long Zi was shocked, if this is the case, they are very likely to be poisoned, and no one knows what the exhaust gas of the drug research center will be.

"yes, go back, they're venting just now, and if I'm right, they're exhausting every midnight. Xu San said as he ran, obviously, he ran very fast, and he was panting.

"Third Brother Xu, come out quickly, Ozu come out quickly. "The dragon is also very anxious, it can be imagined, the gas that is only emitted at midnight must be poisonous, otherwise, there is no need to collect it, just discharge it at any time.

The three of them finally got out of the cave and found a place to rest under the entrance of the cave.

"Now it can be basically confirmed that under the cliff over there is the backup entrance and exit. But why don't you look at it like it?" Xu San said.

"What do you mean, this exhaust pipe is laid along this alternate exit tunnel?"

"Yes, you see, although this entrance to the cave is still a little far from the cliff over there, the further you go in the cave just now, the more the cave turns that way. So this cave may not be very far from the entrance and exit tunnels...... Xu San analyzed.

"Well, I agree with your analysis, but why don't they put the exhaust gas directly into the seawater, why should they put it in the air?"

This is what the dragon is puzzled about, isn't it safer and more hidden to drain in the water than in the cave?

"There must be reasons that we don't know, for example, maybe some gases are not soluble in water and have to be put into the air. For example, this cave has other functions, and the exhaust gas has to be discharged here ....... Xu San said, "Let's ignore this problem for now, let's find an alternate entrance and exit first." ”

"Let's go, go over there and put the microdrone down and check it out. Ryuko said, pointing to a small platform on the edge of the cliff.

The east side of the whole island is actually one side of this mountain, the steep east slope is about 1,500 meters, and the place where the northeast and southeast connect and extend, gradually flattening.

To the east, that is, at the very apex of the big egg, it was as if the big egg had been slashed, cutting out a vertical cliff about three or four hundred meters wide. Under the cliffs, the waves roll and the waves rumble. It looks like it's straight underwater, and there's no reef or anything like that. The water is deep enough that it's a great place to do secret imports and exports.