When an insurance agent (Carlos Chan) is called to visit a couple’s (Anthony Wong and Karena Lam) home to follow up on a life insurance policy, he discovers their son’s corpse hanging in the bathroom. Principled and kind-hearted, he suspects that the child may have been murdered. As he digs for the truth, the tables are turned and he’s forced into a psychological battle of wills. 保险经纪叶永信〔陈家乐饰〕被神秘客户指定跟进保单,在上门拜访时,亲眼目睹客户儿子吊死在半空,正直的他认定客户为诈取保险金而滥杀儿子,决心向这对夫妇——朱重德〔黄秋生饰〕和沈子玲〔林嘉欣饰〕展开追查,凭一己之力将犯人绳之于法,没料这颗正义的心刚好是敌人反击的筹码。当叶永信以为自己逐步迈向真相之同时,恐吓事件接二连三地发生,危险向他以及身边的人逼近,更一度深化他对犯人的恨意,使他逐渐迷失在善恶之间…