When someone hacks into the FBI's computer crime division Cyber; Directors decided to round up all the hackers were able to do this. When he's saying because it's the best July 4th agents are not around so they can get in trouble when people get the hackers. So he instructs them to get local PD'S to take care of it. And one of the policeman John McClane they ask is who is tasked with bringing a hacker named Farrell to the FBI. But as soon as he gets there someone starts shooting at them. McClane manages to get them out but theye are still being pursued. And no'chi when McClane to Washington that the whole system breaks down and chaos ensues.