We all experience birth, old age, sickness, and death. Yet have you ever wondered who determines the time of our death? Respected pharmaceutical doctor Kong Tung Kin starts up his own clinic after a drug trial incident. One day, he is approached by Toi Fung, who claims to be Satan, for a patient’s life. Refusing to do so, he suggests handing over his own. His reaction takes Fung by surprise. With a view to getting to know more about human beings, Fung interferes with Kin’s life, including his family and career. In addition, he runs after Fong Siu Fong, a nurse Kin has been secretly in love with. Later, Kin sells his soul to Fung for money and fame. As time goes by, he starts to become a totally different person, losing his kindness without himself knowing it.