动作巨星元豹(陈奕迅 饰)走红二十余载却从未得到过最佳男主角,因与泰国黑帮老大“八面佛”交好而被怀疑参与跨国贩毒犯罪,铁杆迷弟铁柱(李荣浩 饰)通过擅长“潜规则”的副导(崔志佳 饰)潜入元豹新电影的剧组,努力配合警方收集证据想为偶像洗脱嫌疑。在经历了恋上女一号童童(李一桐 饰),得罪元豹经纪人泰格(陈国坤 饰),晋升成为男二号,目睹偶像用替身、耍大牌等一系列啼笑皆非的“娱乐圈初体验”之后,铁柱也终于离案件更近了一些……ZHU (Ronghao LI) from China, as a huge fan of Hong Kong cinema, has always dream of become a cop like in the movies, who unfortunately failed the fitness exam in China's Police Force selection because of asthma. Zhu settled for the next best thing, working as a PI (private investigator). When he was working a case in Hong Kong, he fell into the hands of the Hong Kong Police, and was coerced into becoming an undercover informant, to investigate the international action movie star, Zhu's hero, BAO (Eason CHAN). According to a tip-off, Bao had been interacting closely with the renowned Thai drug lord, EIGHT-FACED BUDDHA (Jifeng ZHENG), and they were suspected of using movie-making as the front for trafficking. Zhu was so determined to clear his idol's name, he accepted the mission and started investigating by joining the film crew. As Zhu got closer to his idol, he realized that Bao's fierceness and talents were all movie magic, while the real Bao was a man with inferior smartness and ...