What will a man do when torn between love and duty? Hui Wai Sam (Bosco Wong) is an officer in the Witness Protection Unit (WPU). He is assigned to protect Kiu Chi Lam (Linda Chung), a cellist who is the daughter of wealthy businessman Kiu Kong San (Paul Chun), after she witnesses the attempted killing of her father's brother. Chi Lam has already been living with a tremendous amount of guilt over the death of her brother at a young age, but through Wai Sam, she begins to feel happiness again. Despite Kong San's opposition, Chi Lam and Wai Sam begin a romantic relationship.