Zhang Taishan (Lee Joon-gi) is a third-rate gangster who gambles, drinks and sleeps with others, and has a very bad life. This self-destructive life changed because of the appearance of Xu Renhui (Park Ha-sun), his first love girlfriend who had been away for many years, told him that he had an 8-year-old daughter who was now suffering from leukemia and needed him to match her blood type. Zhang Taishan's dead heart was rekindled by the appearance of his daughter. To everyone's surprise, Taishan's bone marrow matched that of his daughter, and the hospital immediately arranged a date for the operation. At the same time, a huge conspiracy was waiting for Zhang Taishan. He was knocked unconscious at a murder scene, and when he woke up, the police arrested him for murder. He understood that this incident was actually the work of the gang boss, and he had to take the blame for him and go to jail for him. Unlike before, Zhang Taishan now has one more concern in his heart, that is, his daughter. There are only two weeks left before the bone marrow transplant, and the agreed time is getting closer and closer, and Zhang Taishan must escape...