Siheyuan: I, Jia Dezhu, Have Returned from the Army.

Jia Dezhu served as a soldier for fourteen years, and had both meritorious service and injuries. In 1949, he changed his job and returned to Sijiucheng. He was assigned to the security department of the steel rolling mill and was also equipped with a sign-in system. The enemy agent wanted to blow up the factory, so he used his eagle eye to find the tunnel; there was no clue about the serial murders, so he used the system to identify the real culprit; the deputy director made trouble everywhere, but he relied on recordings to successfully counterattack. Others change jobs to be stable, but what he changes jobs to do is to uncover all the ghosts hiding in the dark one by one.