"lucid dream" (Lucid Dreaming) is the state of being awake when dreaming, also known as Qingming dream. The film tells the story of a crime thriller in which the father who lost his child three years ago looks for clues in his dreams through lucid dreams. In lucid Dream, Gao Su plays Dahao as a warm-blooded journalist. Once he keeps an eye on something in the workplace, he will pursue it to the end. After losing his son, he looks for clues through lucid dreams, showing the image of a lonely father. Xue Jingqiu will play the role of Fang Xie, a policeman who is interested in strange events, and he is also very active in helping Gao Su after learning about the incident. Jiang Huizhen plays Su Xian, a friend of Dahao and a psychiatrist, who guides Dahao in his lucid dreams. The mysterious figure hovering around Dahao is played by Park Youtian. Sung Bi, a 70-year-old retired gangster who has actively helped Dahao because of past karma, is played by Park in-hwan. And Qian Zhenhao will play Zhao Mingzhe, the chairman of the big group with secrets.