Prison No. 7 Is located in the seventh section of the XXX Labor Reformatory in the Badain Jaran Desert in Inner Mongolia, China. It is commonly known as Prison No. 7.
Everything is gray here...
The sky is gray, the high walls are gray, the iron bars are gray, and there are gray power grids. The prison police have gray faces and wear gray uniforms. The armed police are fully armed and guard the criminals with gray, blue and white lines.
The endless desert is covered with sand in the distance and rocks nearby. The labor camp is a mine. For more than eight hours a day, the men who can still move in the prison come here to "work".
Our story takes place in such a gray world...