Ten years ago, Tong Waichong and Shum Aoming joined the ICAC together. They were trained together and they were brothers. Aoming was injured in a private act, and he resigned soon after, and has not been heard from since. Ten years later, Waichong has been promoted to the chief investigation officer, and led his subordinates such as Lee Zhunyi to maintain integrity and justice. When Waichong investigates a suspected bank employee corruption case, he discovers that Aoming is involved. It turned out that Aoming, relying on his past investigation experience in the ICAC, helped the criminal group to avoid the investigation of various criminal and anti-corruption agencies for many times. Waichong is distressed that his friend forgot his original intention of joining the ICAC to defend fairness and justice, and vowed to bring the criminal group to justice!