In Shanghai in the 1930s, gangs were entrenched, foreigners set up traps, and spies were lurking. Crime spread wantonly in the shadow of the ten-mile foreign market. Zhong Lang, the "Tiger Detective" of the patrol room who was once ruined due to a miscarriage of justice, reorganized the detective team with the help of the clever young detective Han Fei and the medical professor Yu Shengnan who is proficient in forensic and criminal investigation techniques. From the murder case of the "Slitthroat Devil" that reappeared in the world, to the sniper mystery behind the gang fight, from the black gun conspiracy in the arsenal to the assassination plan of the Japanese spy, they traveled through the open guns and dark arrows in the concession and the bloody fog of the city, using courage to break the situation, using technology to pursue the murderer, seeking the truth for the innocent in the dark age, and holding a sharp sword for justice.
