After an accident, Cheng Shi returned to the French Concession in Shanghai in 1920 during the Republic of China! Becoming a patrolman, he solved two murder cases in two days, thus gaining the appreciation of Shanghai tycoon Huang Jinrong.
Immediately afterwards, a man died in an abandoned factory. His throat was cut and he died, but judging from the blood splattered around him, there was no trace of human existence.
As his investigation began, he learned about another secret room murder and the murder in the hotel. The difficulty of the case gradually became more and more difficult. He must solve the case as soon as possible...