From a camping trip, a college girl took home an ancient rope to use to keep her torn backpack in place, not knowing it was used by a disgraced scholar to hang himself with decades before. The scholar's ghost resurrects at her school and befriended her and her two friends, and teaches them the importance of academic success, love, family and friendship.

社会上甚有地位的裘氏一族正准备迎接一场盛大的订婚派对，一位不速之客贾探员（古天乐 饰）却突然到访，并带来少女张小娟一尸两命的自杀命案，划破了裘家欢乐的气氛。裘家上至老爷（曾志伟 饰）太太（毛舜筠 饰）少爷（林家栋 饰）小姐（吴千语 饰），下至管家（罗兰 饰）均表示从不认识张小娟，岂料贾探员竟凭着死者的一本日记和一张照片，将裘家众人的华丽皮囊一一扯下，揭示出每人都跟死者有着莫大的关连！
一场华丽的世纪夜宴如期举行，一片欢乐下，这名探员的到访，会彻底影响裘家的世纪盛宴吗？
电影改编自英国著名舞台剧《An Inspector Calls》。

Old Mr. Lo has three sons and the youngest one Lo Kung is his favorite. However, Kung does nothing but fool around all day long. Old Mr. Lo is very annoyed about this. The relationship between father and son is thus affected. So on Kung's birthday, his two brothers decide to play a joke on him. They trick him into believing he has won the lottery. Kung is so happy that he spends a tremendous amount of money. When he realizes he is in huge debt, he pretends to go insane and the whole family believes him.