Han Qing is a cop in the Sanhe Criminal Investigation Team. Known for her serious demeanor and focus on work, she is nicknamed "Unhappy." She has a strong partnership with her colleague, Zhong Wei, with whom she has worked for many years. However, Zhong Wei goes missing after tracking a suspect, and it has been nearly two months since she has heard from him. Amid the anxiety and frustration, Han Qing deals with other cases while not giving up any clues related to Zhong Wei. A newly emerged murder case catches Han Qing's attention, leading her to suspect that it is linked to Zhong Wei's disappearance. Despite countless obstacles in the investigation, the true culprit eventually surfaces, and what Zhong Wei has been through gradually becomes clear. Unraveling the links between the three major cases of disappearance, murder, and drug trafficking, the police uncover a meticulously organized network of criminal groups and the secrets hidden behind it. The Sanhe Criminal Investigation Team work together to solve the entire case in one fell swoop, capturing all the criminals involved.