Humanity left in a spaceship. Those who stayed behind built a wall in the north.
Within the walls are nuclear power plants, synthetic food, and mechas. Beyond the walls lie beasts, ruins, and the secrets of an old world.
When he was eighteen years old, Chen Du read a line in half of the notebook left by his father: His road is outside the wall.
There was something in his blood that had no precedent or solution, and it was changing him day by day. The notes say that the answer is not in the wall, on the other side of the beast, or in the ruins of the old world.
He started out as a farm laborer. Step on the ridge, move boxes, carry a gun, and walk out of the wall step by step. He has a pair of ears that can hear that others cannot. He knows before anyone else where the beasts are coming from, how many there are, and where they are going.
No one believed the words of a new farm worker. Until he was right so many times that he could no longer be ignored.
Every time I go out to the city, I learn one more skill. Every time I go back to the city, I bring back a few more answers.
Outside the door, someone was waiting for him to come back.
