- Male Protagonist: Lu Zheng - Leader of the Serious Case Team of the Municipal Public Security Bureau. He is 30 years old. He has a shallow scar on his left eyebrow bone. His personality is cold on the outside and hot on the inside. He is vigorous and resolute when handling cases. In private, he feeds stray cats in the area. He is psychologically traumatized by the sacrifice of his partner ten years ago and has an almost paranoid obsession with "missing clues".
- Heroine: Su Wan - The chief medical examiner of the Municipal Forensic Medicine Center, 28 years old, returned from studying abroad, and can reconstruct the crime process through autopsy details. He seems to be so calm and "unhuman", but in fact, because he has witnessed his relatives being misjudged, he is determined to "let the dead speak", and secretly likes to plant mints on the balcony.
