Live Free or Die

In the aftermath of a sudden and mysterious blackout at the FBI Cyber Division headquarters, Deputy Director Miguel Bowman (not specified) swiftly dispatches local law enforcement agencies nationwide to apprehend high-level computer hackers. NYPD Detective John McClane (not specified), assigned to New Jersey, is tasked with retrieving Matthew Farrell. As McClane arrives on the scene, a coordinated attack by assassins hired by Thomas Gabriel, a notorious cyberterrorist leader, targets them. Despite being outnumbered, McClane and Farrell manage to escape unscathed.

As they make their way to Washington D.C., Farrell reveals that he had been working on an algorithm designed to breach a specific security system for white hat purposes. Meanwhile, Gabriel issues a chilling threat to the U.S. government, simultaneously commandeering transportation grids and the stock market nationwide. Farrell realizes that this is a "fire sale," a cyber attack specifically engineered to cripple the nation's infrastructure. As they approach DHS headquarters, Mai Linh, posing as a dispatcher, reroutes their transportation into a helicopter ambush. McClane valiantly fends off the attackers and destroys the helicopter.

As they continue on their journey, Farrell shares his concerns about Gabriel's next move with McClane, deducing that the cyberterrorist will target the nation's power grid. They set course for a utility superstation in West Virginia, only to discover it under the control of Linh's team. McClane and Farrell engage in a fierce battle, ultimately killing Linh's team and McClane exacting a gruesome revenge by locking Linh into a car that plummets from an elevator shaft and explodes.

As Farrell works to slow down the damage by hacking into the hub computer, he manages to trace Gabriel's digital trail and uploads his image to Bowman. McClane uncovers a dark secret: Bowman and Gabriel once collaborated at the Department of Defense, with Gabriel serving as the chief programmer for infrastructural security. Despite identifying vulnerabilities in America's network infrastructure that made it susceptible to cyber warfare, Gabriel was ignored and ultimately fired due to his unorthodox methods. His dismissal sparked a burning desire for revenge.

Enraged over Linh's demise, Gabriel redirects natural gas pipelines to the superstation, aiming to kill McClane and Farrell. They narrowly escape as a massive blackout ravages the Eastern Seaboard. Undeterred, McClane and Farrell travel by helicopter to Baltimore, seeking the expertise of renowned hacker Frederick "Warlock" Kaludis. Warlock analyzes the code written by Farrell for Linh, revealing it serves as a key to accessing data at a Social Security Administration building in Woodlawn, Maryland. Through a series of digital breadcrumbs, Warlock tracks Gabriel's location.

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As it turns out, the seemingly innocuous Woodlawn building conceals a sinister purpose - an NSA facility designed by Gabriel himself to safeguard the nation's personal and financial records against cyber attacks. When the FBI's systems go dark, Woodlawn springs into action, downloading a vast array of financial data that Gabriel plans to plunder. Meanwhile, he exploits their connection to uncover the whereabouts of McClane's estranged daughter Lucy, whom he promptly kidnaps. This sets off a chain reaction as McClane and Gabriel engage in a virtual showdown, with McClane issuing a dire warning: "You will lose."

Undeterred, McClane and Farrell embark on a perilous quest to infiltrate Woodlawn, racing against time to prevent Gabriel from exploiting the facility's secrets. When they finally breach the main server, Farrell swiftly encrypts the compromised data before falling into Gabriel's trap. The cunning villain then spirits away with both Farrell and Lucy, leaving McClane to give chase.

As the pursuit intensifies, McClane commandeers their mobile command center and seizes control of the F-35B Lightning II's communication system. Gabriel orders the pilot to launch a devastating attack on McClane's truck, but fate intervenes as falling debris reduces the jet to scrap metal. Miraculously, McClane survives the ordeal and tracks Gabriel to a nearby hangar.

There, the stakes are raised as Gabriel demands that Farrell decrypt the stolen financial data. When Farrell refuses, Gabriel cold-bloodedly executes his accomplice and threatens to eliminate Lucy unless he complies. Just as all hope seems lost, McClane bursts onto the scene, dispatching two of Gabriel's henchmen before succumbing to a gunshot wound inflicted by Emerson. As Gabriel positions himself for the kill, McClane seizes the initiative - literally. The bullet meant for McClane instead finds its mark in Gabriel's chest, ending his nefarious plans instantly. With Emerson eliminated by Farrell's quick thinking, the FBI arrives to put an end to the chaos. In the aftermath, McClane expresses gratitude to Farrell for saving Lucy, and it becomes clear that a romantic spark has been lit between McClane and the young woman.