左勾拳（陈展鹏饰）背负家破人亡的伤痛重返城寨，希望寻回失踪多年的姐姐。昔日成长的地方转眼已成恶势力横行的三不管地带，他隐藏八极拳后人的背景，以新身份结识了巴辣的电发店老板娘刁兰（胡定欣饰）、牙医段迎风（袁伟豪饰）和及运水工人毕得了（林子善饰），又得功夫高强的玉波凤（元秋饰）赏识。为了重整城寨秩序，勾拳集众人之力成立了福利会力抗恶势力，却因此跟玉波凤儿子，黑市拳王龙成虎（伍允龙饰）起了冲突。当一切渐上轨道，黑帮核心人物离奇死于八极拳下，勾拳和刁兰合力调查，发现跟脱衣舞团领班花曼（王君馨饰）有关，继而揭开当年父亲遭害的真相；不过，最令勾拳难以释怀的是，身边人竟是一个极度残忍的杀人组织成员。同时，又被迫与好兄弟上演一场迟了十五年的宿命之战…… Left hook (Chen Zhanpeng ornaments) with the destruction of the pain to return to the city to village, hope to find the missing years of my sister. Where former growth of the blink of an eye has become rampant evil forces three regardless of the zone, he hides Bajiquan descendants of background, with a new identity meet the Rabbah of the electric hair shop boss Diao LAN (Nancy Wu decorated), dentist upwind (yuan Weihao ornaments) and transport workers of water speed the (Alex Lam ornaments), and Kung Fu Qiang jade Bofeng Yuan Qiushi appreciated. In order to restructure the walled city order and hook set of people formed a welfare will against the forces of evil, but so with jade Bofeng son, black market boxing Long Chenghu (Wu Yunlong act the role ofing) played a conflict. When all gradually on track, the central figure in the gang bizarre died Bajiquan, hook and Diao LAN force survey found with strip dance captain flowers (Wang Junxin decoration) the man, and then uncover the truth when father evil; however, most make hook haunting, beside the person unexpectedly is a extremely cruel killing members of the organization. At the same time, and forced to perform a good brother and a late fifteen years of the fate of the war......