Young and idealistic Liu Ziming joins a police division to fight crime, only to find routine investigative work far duller than expected. But as he gains field experience, he grows into a shrewd detective, mentoring newcomers while solving complex cases. Through many investigations, Liu confronts humanity's duality-the good and evil within-evolving into an exceptional captain. His mentor and comrades teach him the weight of a detective's duty. Now, safeguarding justice becomes his pride.