某年7月4日，周末，正在休假的约翰?麦卡伦（布鲁斯?威利斯 饰）接到一个新任务：逮捕黑客马特?法莱尔（贾斯汀?朗 饰），然后送到FBI那里接受审讯。 　　其实，事情并没有看上去那么简单：极端恐怖分子经过周密策划之后，准备利用黑客技术，在美国独立日当天让全美国的计算机系统集体瘫痪，从而达到他们控制全球的阴谋。而且，幕后黑手托马斯?加布里埃尔（提摩西?欧里芬特 饰）为了阻止麦卡伦插手这件事情，为他准备了一大堆机关障碍，其中包括绑架他的女儿露西。 　　老英雄遇上了新问题，在马特?法莱尔的帮助下，麦卡伦继续“生猛”……

西蒙（杰里米?艾恩斯 饰）是个头脑慎密，心狠手毒的恐怖分子。为了实现一场惊天大阴谋，他先是制造了一起爆炸案。在警方紧张破案之际，他又给警长约翰?麦卡伦（布鲁斯?威利斯 饰）打电话，声称警方必须听从他的一系列指令，否则他将继续在全市搞爆炸活动。 　　在杂货店老板宙斯（塞缪尔?杰克逊 饰）的帮助下，麦卡伦完成了西蒙的一系列指令，多次死里逃生。然而意犹未尽的西蒙，命令麦克莱恩去拆除街心花园的炸弹，又宣称在纽约市一所小学校内安放了炸弹。警方和市政官员几乎全部出动，去各小学疏散学生，搜寻炸弹。 　　麦卡伦逐渐对西蒙一个又一个的指令产生疑虑，他终于发现西蒙调动全市警力背后的真相……

2047年的巴黎，大部分人群都已经习惯将时间浪费在网络游戏上，将虚幻的网络与现实紧密联系起来，甚至已经将网络世界作为他们的主要生活，把现实抛到一边这些以网络生活为主的人群被称为“连接人”。而由于人们几乎将所有时间都耗费在虚幻的网络中，忽视了个人生活的健康与饮食，大多数的“连接人”要么丰腴腻脂，要么骨瘦嶙峋，人类整体的寿命也缩减到四十来岁。

百年之前，一系列的连锁巨变摧毁了多数的地球文明，将世界带入了无尽的黑暗时期。剩余的幸存者试图回到过去改变引起这一切毁灭事件的进程。

　　Theo Abrams is an ex-Cape Town fireman suffering from severe Post-Traumatic Stress Disorder. Unable to return to work due to the psychological trauma sustained during a failed rescue mission, an increasingly frustrated and volatile Theo's world is rocked when one morning, he wakes up next to his wife's murdered corpse with no recollection of what transpired and all evidence suggesting that he's killed her. When the police label him as the prime suspect, Theo goes on the run, and is soon being hunted by Deputy Chief of Police, Alan Shard, a notoriously ruthless soldier of the law, who is hell-bent on catching Theo as one last act of service before he officially retires. However, when an unknown third party is thrown into the mix, Theo discovers an alarming connection between the sinister forces hunting him in an attempt to silence him permanently for a reason he can't comprehend; and a recent investigation his wife was conducting into a global armament contractor. When connecting the dots becomes a matter of life and death, Theo becomes embroiled in a desperate fight for survival and must figure out who really murdered his wife before a terrifying conspiracy changes the course of a nation forever.