《极斗4之暴杀令》故事讲述香港的家庭暴力和女性被侵犯事件，各人对事发的反应，当中有人选择以暴易暴，替天行道，其实为社会和法律不容，因为香港无蝙蝠侠，不可以执行私刑，其实电影带出社会问题令人反思。 《极斗3之雅博渡口》是「与神格斗」后，这次《极斗4之暴杀令》是「与仇恨格斗」，电影主题与性侵犯有关，并表明调子相当灰暗。“极斗4之暴杀令”有点像80年代经典电影【山狗】，山姆哥借电影致敬。
金融公司遭十亿恶意贷款，首次讨要无果后，讨债公司老板瑞秋挺身而出。她集结布朗克和席德组成一支精英小队，成功夺取硬盘数据，锁定债主曼尼的隐秘资产。随后，小队展开一连串精密操作，曼尼的资产帝国被迫冻结，而曼尼也终于现身谈判同意还钱。但当曼尼付清了债款，金融公司却迟迟未将曼尼的资产归还，气急败坏的曼尼将瑞秋擒获试图进行要挟。精英小队是否能成功将瑞秋救出，而曼尼又将受到怎样的恐怖惩罚呢？
Kyohei Aizawa, an assassin for a covert non-governmental espionage group in Japan called "SEEK", is grieving over the loss of his girlfriend from a tragic plane accident. The leader of "SEEK",Ryo Mikumo, contacts him for an emergency mission; save a fellow agent, recover a new highly explosive liquid called "RDX@", stop a ruthless Yakuza leader, Sojiro Kotsuki, and his gang before they take over Japan. Although the Ninjas were thought to have disappeared... the new breed of assassins live on helping to protect Japan and all that is right; the Ninjas are coming soon.
