史上最棒的圣诞庆典

　　At Christine's funeral, her foster son suddenly shows up, a grown-up man with whom the family has been out of contact for quite some time. He brought a letter, stating that Christine wants to be buried in Wentelen, to the bewilderment of her biological children, and even more so to that of her husband. In addition to that, all the relatives are surprised that the foster son of Christine apparently maintained a correspondence with Christine. Nevertheless, Christine's last wish is respected, and they decided to bury her in Wentelen, and wish to do so traditionally, meaning: walking behind the hearse. During a walk of several days, all the relatives (foster sisters, foster father, alleged friends and real ones, the foster son, lovers) have enough time to get to know each other better. Because in the end they have no other conclusion than that nobody really knew anyone. Old intrigues are dug up, the foster sisters finally learn why the foster brother just disappeared from the family, and they can begin to develop a real image of the mother. Once Christine's final resting place is reached and she is buried, all family ties, good and bad, are shaken around.

2043年7月1日，犯罪大王将军（卢惠光饰）被捕，一星期后由铁面无私的法官余铁雄（张卫健饰）主审。将军特派其黑社会爪牙健（郑伊健饰）返回50年前寻找铁雄，并将其洗脑使他无法进行审判。政府知情后特派飞龙特警铁面（刘德华饰）、扫帚头（张学友饰）及发达星（任达华饰）返回1993年去保护铁雄。 　　时大雄为93年一中学长期留班生，常遭同学余忌安（许志安饰）作弄毒打，只有女友采妮（杨采妮饰）对他真心。飞龙三特警混进学校，扫帚头当上老师，铁面做大雄同学，星则任大雄跟班，帮大雄打赢忌安，并向他套取铁雄下落，但大雄却表示校内并无铁雄此人。在这时健亦扮成老师混入学校，另一边大雄母亲要改嫁理查德余……最终飞龙特警能完成任务吗？