Bian Yunpeng, who became a puppet soldier at the age of sixteen, lived a miserable life in the Japanese stronghold. At midnight, the sound of neat "ghost troop" drills came from the ground. The Japanese army was suspicious and their morale was on the verge of collapse. He was forced to explore the abandoned coal mine with the ruthless Lieutenant Ono, but gradually discovered that the real "ghost" was not a supernatural thing, but an underground contest of wisdom. He must find his way out and his way back in the maze of this psychological war.
