The special murder case that failed to be solved in 1997 reappeared 13 years later. The criminal guard Zheng Rong (played by Chen Jianbin), who had never tracked down the real murderer, was hit hard and left the front line. The rookie policeman Lu Xingzhi (played by Chen Xiao) has shed his immaturity and has become a meticulous criminal investigation expert. The coincidences of the case brought the master and apprentice together again to work together to hunt down the real murderer. The play is adapted from Lou Xiaopeng's novel "The Light of the Dark Night".