On Christmas Eve 1990, just two years after the infamous Nakatomi Tower incident, former NYC police officer John McClane, now serving with the LA Police Department, is anxiously awaiting the arrival of his wife Holly (played by Bonnie Bedelia) at Dulles International Airport. Unbeknownst to him, lurking nearby is reporter Richard Thornburg, who had previously exposed Holly's identity to the notorious Hans Gruber during the Nakatomi crisis.
In the airport bar, McClane's instincts kick in as he notices two men dressed in Army fatigues acting suspiciously. Driven by concern, he follows them into the baggage area, where a violent shootout ensues. In the chaos, McClane manages to kill one of the men, Oswald Cochrane (John Costelloe), while the other manages to escape. After calling in Sergeant Al Powell (Reginald VelJohnson) to check Cochrane's prints, McClane discovers that Cochrane was supposedly a casualty in Honduras. Desperate to alert airport police captain Carmine Lorenzo (Dennis Franz) about the potential threat, McClane explains that Cochrane had brandished a Glock 7, an invisible weapon that evades x-ray detection. However, Lorenzo, dismissing McClane's concerns, is more interested in enjoying the Christmas festivities and refuses to take action.
Meanwhile, a group of former U.S. Army Special Forces, led by Colonel William Stuart, establish a base in a nearby church. They unethically breach the airport's air traffic control systems, cutting off contact with flights, and severely compromising runway lights. Their intent? To free General Ramon Esperanza (Franco Nero), a drug lord being extradited to face charges in the United States.
To support their plan, Stuart's crew, which includes Garber (Don Harvey), Miller (Vondie Curtis-Hall), Burke (John Leguizamo), O'Reilly (Robert Patrick), and others, demands a Boeing 747 cargo plane for their escape. As McClane learns from reporter Samantha 'Sam' Coleman (Sheila McCarthy) that Stuart had funded Esperanza in his rise to power, he realizes the depth of the conspiracy he's up against. With the clock ticking and his wife on a plane running low on fuel, McClane gears up to take on the terrorists, forming an unlikely alliance with janitor Marvin (Tom Bower) to navigate the airport's expansive layout.
McClane’s exploits lead him to a showdown with Stuart's mercenaries and a desperate battle to regain control of the airport. After a series of intense confrontations, including a heart-stopping moment at an unfinished antenna array, where McClane manages to rescue Leslie Barnes (Art Evans) while eliminating several henchmen, the stakes escalate dramatically. When Stuart blows up the antenna and orchestrates a catastrophic crash, McClane races against time, to save the circling aircraft.
Facing multiple threats, including the shocking betrayal of the Special Forces team, McClane's resourcefulness shines through. He commandeers a snow scooter for a thrilling pursuit across a frozen lake, engaging in a harrowing battle with Stuart as they fight for control of the escape plane. Ultimately, McClane's tenacity proves vital, igniting a trail of fuel to lead to an explosive climax that enables the planes to land safely, to the cheers of their grateful passengers.
In the aftermath of the chaos, as the dust settles, McClane and Holly share a heartfelt reunion, reminding everyone that love and bravery can prevail even in the most perilous situations.
