Lin Yan, the chief female forensic doctor in modern times, traveled to the French Concession in Shanghai while investigating old cases from the Republic of China, and became a rookie forensic assistant to find her missing brother. There are no modern instruments here, only rusty tweezers and the contempt of foreign detectives; there is no impartial handling of cases, only secret operations by Chinese and foreign forces. But she grabbed a mini ultraviolet pen and half of her grandfather's old diary, and used modern forensic knowledge to tear through the layers of disguise - breaking the loopholes in the "suicide by falling from a building", revealing the truth about the "silver hairpin to detect poison", and using the diatom code to find out the real culprit who dumped the body.
On the way, she met Shen Tingzhou, a Chinese detective who dared to resist foreign power. The two went from probing to working side by side. She performed an autopsy to find irrefutable evidence, and he overcame obstacles and approached the "Black Peony Smuggling Network" step by step. This network contains clues to her brother's disappearance, leads to the secret of her time travel, and is even connected to the unfinished mystery of the corpse burning in her grandfather's diary.
In the troubled world of the concession, will she abide by her original intention of being a forensic doctor and pursue the murderer, or will she choose to return to modern times? In the end, she and Shen Tingzhou let the dead "speak", found justice in the fog, and found a destination in the next life.
