高老大（陈萍 饰）是神秘杀手组织“快活林”的当家，孟星魂（宗华 饰）和叶翔（凌云 饰）都是她一手栽培出来的刺客，对她忠心耿耿。某日，孟星魂接受了刺杀江湖盟主孙玉伯（谷峰 饰）的任务，却在执行任务之时结识了名为小蝶（井莉 饰）的美丽女子，两人一见钟情。 　　孙玉伯和飞鹏堡有着不共戴天之仇，为了报仇，孙玉伯决心比武招贤，孟星魂在擂台上胜出，得到了孙玉伯的赏识。律香川（岳华 饰）是孙玉伯的养子，孟星魂和他联手，最终歼灭了飞鹏堡。正当孟星魂准备执行刺杀任务之时，得知了小蝶竟然就是孙玉伯的女儿，与此同时，律香川人面兽心勾搭高老大和飞鹏堡，企图加害孙玉伯。Two clans compete for dominance over the martial arts world in this classic of violent swordplay and political intrigue. A complex tale of deception and double crosses. Killer Clans leaves viewers guessing every step of the way. Masterful fight choreography from Yuen Cheung Yan (Yuen Clan member and brother of Yuen Woo Ping) and Tong Gaai fills the screen with bloody sword fighting and imaginative weaponry, delivering both great drama and fantastic martial arts.