In 1932, the French Concession of Shanghai was undercurrents surging, rivers and mountains were turbulent, and the political situation was precarious. Inspector Gu Changfeng and genius female coroner Su Manqing joined forces for the first time due to a bizarre murder case, but accidentally got involved in the serial poisoning conspiracy of the mysterious organization "Qingluan Association". From the Paramount to the tailoring shop, from the "Kiss of Death" perfume to the acoustic detonation device, every corpse was engraved with the Qingluan totem, and every drop of poison pointed to a crazy plan to subvert Shanghai. Justice and family affection collided fiercely, and when the adoptive mother's last letter awakened the soul swallowed by hatred, this dark night chase concerning the destiny of the whole city had just ushered in a true reversal.