Synopsis
Au Yeung Wai Yip (Louis Koo) is a private detective who has been focusing on missing persons and adultery investigations for many years. One day, he received a "special" job: the owner of a travel agency had asked him to investigate his girlfriend, who happened to be Au Yeung Wai Yip’s wife. Unable to withstand his inner torment, Au Yeung Wai Yip gave up on another ongoing case - a client's search for his missing fiancée - and went to the hotel to catch the adulterer. Unfortunately, the marriage could not be saved, and the client's fiancée was killed. A seemingly ordinary affair has turned into a murderous incident!欧阳伟业（古天乐饰）是一名落魄的私家侦探，委托人都是找他处理通奸、寻人、宠物失踪等微不足道的小案。这天他收到一宗「特别」的委托：一名旅行社老板要求他调查自己的女朋友，而这名女子不是别人，竟是欧阳伟业的妻子关咏心（周秀娜饰）。私家侦探习惯以冰冷的目光为客户寻找真相，然而要面对自己的婚姻真相却感到寸步难行。敌不过内心煎熬，欧阳伟业放弃正在进行的另一宗案件——为客户寻找其失踪未婚妻——的调查，前往酒店捉奸。没想到最后婚姻保不住，客户的未婚妻更在他离开现场后被杀，原以为的普通出轨事件竟演变成一场谋杀！