Five years ago, Shen Yi, who was still a student, was sketching on the street. However, a painting caused Haicheng detective Lei Yifei to be exposed as an undercover agent and he was killed. And Lei Yifei happened to be Du Cheng's long-time friend and confidant. Five years later, the guilt became heavier. In order to find out the truth, Shen Yi accepted the invitation of Director Zhang of the Public Security Bureau and became a portraitist of the Interpol Team. Under Zhang Ju’s persuasion and arrangement, Du Cheng had to accept that he became a colleague with Shen Yi, but he was still full of annoyance. On the way to find out the truth of Lei Yifei's life and death, the two people gradually untie their knots and work together to uncover the dust-covered secrets.