The police are investigating a case that involves a death directly caused by a rare bug known as the bullet ant. In order to clear his name, Tan Jingtian, an Insect toxicology graduate becomes involved in the bizarre investigation and collaborates with forensic doctor Jin Ling. As they dig deeper, they uncover the mystery behind his own identity. Along with police captain Chen Han and the other detectives, they trace every clue as they solve one case at a time to uncover the murderer that has been in hiding for many years.
Five years ago, painter Shen Yi’s sketch of a child led to the exposure and death of undercover detective Lei Yi Fei, Du Cheng’s close friend. Unable to recall the woman who asked him to draw the child, Shen Yi lives with guilt. Now, he joins Haicheng Public Security Bureau as a portraitist, despite Du Cheng’s fury over his involvement in Lei Yi Fei's death. The two clash as Shen Yi uses unconventional methods to crack cases. As they work together, Du Cheng begins to see Shen Yi’s value, and together, they uncover the truth behind Lei Yi Fei's death, resolving their past conflicts and forming a strong partnership.
