• Shen Yan: Captain of the Municipal Criminal Investigation Detachment. He is calm, ascetic, and logical. He is good at criminal psychological profiling and scene trace analysis. He became taciturn due to an unsolved case three years ago (when his partner died in the line of duty), and there is an unquenchable obsession in his eyes.
• Lu Yu: A genius forensic doctor with a wild and unconventional personality. He is proficient in forensic toxicology, micro-object identification, and even knows hacking technology. He is cynical on the surface, but in fact he has the ultimate pursuit of the truth. His background is mysterious and seems to be related to Shen Yan's old case.
