New York police detective John McClane gets a parking ticket from a rude cop as soon as he arrives at Dulles International Airport in Washington, D.C. Inside the terminal, John learns that his wife Holly’s flight from Los Angeles, California, is a half-hour late. Television sets herald the news that General Ramon Esperanza, a deposed, drug-smuggling Latin American dictator, is being extradited to the U.S. and will arrive in Washington that evening. John bumps into Colonel Stuart, but only vaguely recognizes him. Near Dulles, two of Stuart’s men murder the caretaker at an empty church. In an airport bar, John watches a man slide a suitcase under a table to Oswald Cochrane. When Cochrane leaves, John follows him to a restricted baggage handling area. Nearby, as television reporter Samantha “Sam” Coleman stops Col. Stuart for a comment about Esperanza’s extradition, he rudely rebuffs her. John enters the baggage area and sees Cochrane with an African-American named Miller. When John displays his badge and announces that they are in a restricted area, the men draw guns and a shootout ensues. Cochrane is crushed on a conveyer belt during the struggle, and as Miller escapes, John is arrested by two airport policemen. Taken to security chief Captain Carmine Lorenzo, John demands that airport police set up a crime scene investigation. Wary of shutting down the airport only days before Christmas, Lorenzo minimizes Cochrane’s death as a luggage robbery gone bad, despite John’s claim that one man carried a porcelain Glock 7 pistol that does not show up on airport metal detectors. John returns alone to the baggage area in time to see police carrying out Cochrane’s body. Borrowing a stamp pad from an airline desk, he takes the corpse’s fingerprints, calls Police Sergeant Al Powell in Los Angeles and faxes him the prints. Meanwhile, Trudeau, head of traffic control, tells his controllers the weather may keep airplanes circling overhead for a while. Later, Sgt. Powell telephones John to tell him Cochrane is listed as being killed two years earlier while working as a U.S. military advisor in Honduras. Reporter Sam Coleman recognizes John from the famous “Nakatomi” incident in Los Angeles and follows him to the control tower, where John shows Trudeau evidence that the dead man was a professional mercenary. Capt. Lorenzo tries to convince Trudeau not to listen to him. Suddenly, runway lights shut down and the control tower’s electronic system goes dead. Col. Stuart telephones Trudeau moments later and demands he divert General Esperanza’s airplane to an isolated runway and prepare an empty 747 cargo-conversion airplane for a long flight. Otherwise, he will start crashing airliners. At Capt. Lorenzo’s insistence, Trudeau orders John and Sam out of the control tower. As he leaves, John overhears chief engineer Leslie Barnes tell Trudeau he can reestablish communication by activating the “antennae array” at the airport’s “Annex Skywalk,” which is under construction. In the elevator, when Sam tells John that both he and Col. Stuart brushed her off, John remembers Stuart as the man he bumped into earlier. He stops the elevator and escapes through the roof. Making his way to the basement, John enlists Marvin, a janitor, to provide him with an airport map and the location of the Annex Skywalk. Meanwhile, Trudeau keeps airplanes in a holding pattern above Dulles and Capt. Lorenzo sends Leslie Barnes, along with a S.W.A.T. (Special Weapons and Tactics) team, to the Annex Skywalk. Mercenaries disguised as construction workers ambush the cops and kill them all except Barnes. As a gunman named O’Reilly prepares to execute the engineer, John arrives and shoots the would-be killer. Suddenly, an explosion destroys the annex “antennae array.” Overhead, Holly McClane and television reporter Richard “Dick” Thornberg both notice they are circling the airport with other airplanes. Listening to O’Reilly’s radio, John overhears Stuart threaten to crash an airplane. Cutting in on the colonel’s telephone call to Trudeau, John identifies Stuart by name, and Capt. Lorenzo shouts for McClane to shut up. Stuart recognizes John’s name from the Nakatomi news coverage. When John accuses Stuart of treason, the colonel replies that America’s leaders are the real traitors, because they are undermining the country’s “anti-Communist allies.” Col. Stuart orders his men to reactivate the airport’s landing system, but recalibrate ground level by minus-200 feet. As the only one who can contact pilots overhead, he imitates a ground controller and brings in an airliner for a landing. John rushes onto the runway with two improvised torches and tries to alert the airplane, but fog and snow obscure his efforts. The airplane hits the runway and explodes, killing everyone aboard. Trudeau demands that Barnes figure out a way for them to warn other pilots, then informs John that Holly’s airplane has only ninety minutes of fuel left. Overhead, sensing something wrong, Dick Thornberg tells his TV soundman to cut in on the pilot’s transmissions with his personal radio, but discovers there is no reception. On the ground, Major Grant, a special operations officer who trained Stuart, arrives with a commando squad. Engineer Barnes devises a way to transfer radio frequency to the airport’s “outer marker” beacons that automatically give off signals to aircraft. Barnes successfully contacts the pilot of Holly’s plane and explains the problem. Listening in the passenger section, Thornberg hears everything. When Trudeau gathers his staff in the pilots’ briefing room, John is forbidden to follow, so he returns to the basement and learns from Marvin how to get to the briefing room. Meanwhile, as his military plane approaches Dulles, General Esperanza kills his guard and shoots the pilot, but in the altercation he blasts a hole in the cockpit window. Taking the pilot’s seat, he radios Stuart that he is losing air pressure and has to land quickly. John hears the transmission over his radio. With instructions from Marvin, he hurries through a tunnel to the runway where Esperanza is landing and arrests him as he opens the airplane door. However, mercenaries arrive, send John scrambling for cover, and pull General Esperanza to safety. They riddle the cockpit with machine-gun fire and toss in several hand grenades. John straps himself in the pilot’s seat and pushes the “eject” button, sending him flying into the air a split second before the grenades blow up the plane. The mercenaries drive away, John lands by parachute on the runway, and Capt. Lorenzo’s men return him to the tower. There, Barnes guesses the mercenaries must be nearby, because they were able to react quickly to the general’s distress call. Barnes suggests a likely place is an old church on the west side of the airport, so he and John hurry there, and John kills the sentry. At that moment, Major Grant and his men, along with Captain Lorenzo, surround the church, but the mercenaries slip out the back door and escape on snowmobiles. John kills one man, grabs his semi-automatic rifle, and jumps on his snowmobile. In a firefight with Col. Stuart, John’s snowmobile is hit and catches fire, forcing him to crash into a ditch. Wondering why his rifle was ineffective, he checks the magazine and realizes the cartridges are blanks. Meanwhile, Thornberg contacts his television station by telephone and broadcasts what is happening above Dulles. Passengers in the terminals below panic and stampede. Holly borrows a fellow passenger’s stun gun and knocks Thornberg unconscious. When John convinces Lorenzo that Maj. Grant and his men are part of the terrorist operation, they hurry to the hangar where a 747 has been fueled for General Esperanza’s escape, but the airplane has already taxied onto the runway. Commandeering Sam Coleman’s news helicopter, John is dropped onto the airplane’s huge left wing and stuffs his jacket into an aileron, preventing the airplane from lifting off. Grant and Stuart climb onto the wing to stop him, but in the ensuing fight, Grant falls into the jet engine and John is nearly knocked off the front of the wing. Unscrewing one of the fuel caps and letting the liquid pour out, he drops to the ground. Sitting next to gasoline on the runway, he sets it afire with his cigarette lighter. Fire rushes along the string of fuel and follows the airplane into the air, turning it into a fireball that crashes onto the runway. Airline pilots use the long line of flames to land their airplanes, and John grabs Holly as she escapes down a chute. Captain Lorenzo arrives in time to tear up John’s parking ticket.