8月12日全国上映家喻户晓的大明星杜明汉(王力宏饰)虽然事业发达，人生看似顺遂写意，但他内心偶尔总会感到空虚遗憾。直到有一次，杜明汉的保姆车意外撞上音乐系女学生宋晓青(刘亦菲饰)，宋晓青不先检查伤口，反而弹起古筝的奇怪举动，及弦音中展现出的微妙感，引起了杜明汉的好奇心，他于是决定要跟好友兼乐团伙伴魏志柏(陈汉典饰)一同潜入校园，一探宋晓青的“弦外之音”。 除了得将人人熟悉的大明星改头换面、卧底进入校园之外，杜明汉还得要成功闯过经纪人Joan(陈冲饰)这一关。但各种困难都阻挡不了杜明汉寻找宋晓青的决心。 一下子是学生、一下子是明星，双重身份把杜明汉弄得晕头转向，他将会闹出多少笑话？而他又是否有机会发现，自己与宋晓青的关联，原来都只为知音二字…

　　August 12 released the country's largest known star Duming Han (Wang Lee Hom ornaments) Although the cause of development, success in life seems decent, but he always felt empty inside sometimes regret. Until there is time, Duming Han's nanny school girl accidentally hit the music Song Xiaoqing (Liu Yifei), a Song Xiaoqing without first checking the wound, but a strange bounce Zheng moves and string sounds in the show's subtle sense of curiosity aroused Duming Han He decided to keep up good friend and band partner Weizhi Bo (Chen Handian decorated) with sneak into the campus, to explore Song Xiaoqing's "overtones." In addition to the all too familiar to star a new look, undercover into the campus, Du Minghan have to successfully break through brokers Joan (Joan Chen played) this level. However, difficulties can stop looking for Song Xiaoqing Du Minghan determination. Once a student, once a star, the double identity of the Du Minghan head spin, he will be sudden, the number of joke? Does he have the opportunity to find themselves associated with the Song Xiaoqing, the original word only for the Concert ...

　　单亲妈妈Grace（徐熙媛饰演）这天如常送女儿如婷上学，途中却被悍匪以霍（刘烨饰演）驾车栏腰猛撞，在她半昏半醒、全身无力的状态下，目睹以霍在她屋内大肆搜索，更以凶残手法杀害其女佣！然后把Grace掳走并锁到一个货柜内。以霍逼使Grace交出他的犯罪证据，否则把她全家干掉。惊惶失措的Grace趁无人看守时竭力地把一台损毁的手机重组，奇迹地打出一个求救电话，意外拨通给任职财务公司贷款部职员的阿邦（古天乐饰演）。

　　阿邦的儿子要出国升学，这刻他姐姐Jeanie（陈慧珊饰演）与儿子已在机场等他，正十万火急地赶往机场。对于Grace的求救电话感到半信半疑，随手把电话交给交通巡警辉Sir（张家辉饰演），可惜此时线路出现问题，辉Sir未听清Grace的说话，更惊告阿邦别再戏弄警察。此时以霍突然闯进货柜箱内，幸好Grace能把手机及时藏好，阿邦再接过电话便清楚听到一下枪声，知道事态严重，决定拯救Grace！但当务之急，是要阻止悍匪伤害下一个目标――Grace的女儿，阿邦必需阻止其女儿落入绑匪的魔掌之中，前面将有惊险万分的事情发生，他随时要为了救人而付上宝贵生命……

　　Single mother Grace (Barbie Hsu plays) as usual on this day to send their daughters to school, such as Ting, but was ruthless in the way Hall (played by Liu Ye) to drive back slam bar, half awake in her semi-unconscious, general weakness of the state, witnessed by Huo wantonly in her house search, more brutal way to kill the maid! Grace then abducted and locked in a container. Grace Fok forced to hand over evidence of his crime, or kill her family. Grace of panic when trying to take advantage of unattended damaged phone to a reorganization of a miracle to play a distress call, accidentally dial to the office staff of the Ministry of finance company loans Abang (played by Louis Koo).

　　Abang's son to go abroad to study, this moment his sister Jeanie (played by Flora Chan) and his son have been waiting for him at the airport, is matter of great urgency to rush to the airport. For Grace, was skeptical about calls to hand the phone to traffic patrol Hui Sir (played by Nick Cheung), but unfortunately this time line problems, Hui Sir did not hear the words of Grace, more frightened Abang stop playing, the police report. Then suddenly broke into the container box to Huo Fortunately, Grace can phone possession of a good time, Arbonne will be clearly heard and then received a telephone call about gunshots, that the situation was serious and decided to save Grace! But the main thing is to stop the ruthless hurt the next target - Grace's daughter, Abang necessary to prevent his daughter fall into the clutches of the kidnappers, the front will be extremely thrilling things happen, he is ready to pay in order to save the their lives ... ...