Dr. Mack Lau (Tony Leung) is a cynical person on the surface, but he is actually very delicate and has a strong insight of the world. He despises the injustice of the health care system and runs his own clinic in a red-light district. Indulged in medical science, Mack possess superior medical skills and is passionate in treating underprivileged citizens. Among his patients include a brave policeman, Chiu, his neighbor prostitutes and so on. Aside from healing his patient's wounds, Mack is also willing to listen to their thoughts and become their friend. However, Mack was later framed by his old friend and medical classmate, Roger Law (Alex To), and must face the crisis of his doctor's license being revoked.
醫生劉文（梁朝偉飾）表面玩世不恭，實際上卻是個細膩且洞悉世情的人。他醉心醫學、醫術高明，但厭惡醫療制度的不公，到了紅燈區經營診所，並屢向貧苦大眾施醫德。他的病人中有英勇的警員（劉青雲飾）、風月女子等等。他除了醫治病人身體上的傷痛，也樂於傾聽這羣草根的心聲，成為了他們的好友。但他卻被昔日的好友陷害，面臨吊銷醫生執照的危機。
