On Christmas Eve, two years after the Nakatomi Tower Incident, John McClane is waiting at Washington Dulles International Airport for his wife Holly to arrive from Los Angeles. Reporter Richard Thornburg, who exposed Holly's identity to Hans Gruber in the Nakatomi Tower, is assigned a seat across the aisle from her. In the airport bar, McClane spots two men in Army fatigues carrying a package, one of whom has a gun. He follows them into the baggage area. After a shootout, he kills one of the men while the other escapes. Learning the dead man is a mercenary believed to be killed in action while originally serving with the US military, McClane relates the situation to airport police captain Carmine Lorenzo, but Lorenzo has McClane ejected from his office.
Former U.S. Army Special Forces Colonel William Stuart and other members of his unit establish a base in a church near Dulles. They take over the air traffic control systems, cut off all communication to the planes and seize control of the airport. Their goal is to rescue General Ramon Esperanza, a drug lord and dictator of Val Verde, who is being extradited to the United States to stand trial on drug trafficking charges. They demand a Boeing 747 cargo plane so they can escape to another country with Esperanza in tow, and warn the airport controllers not to try to restore control. McClane realizes his wife is on one of the planes circling above Washington, D.C. with too little fuel to be redirected. He prepares to fight the terrorists, allying himself with a janitor, Marvin, to gain larger access to the airport.
Dulles communications director Leslie Barnes heads to the unfinished Annex Skywalk with a SWAT team to re-establish communications with the planes. Just before reaching the Skywalk, the entire group and Barnes are ambushed by Stuart's henchmen at a checkpoint, and the SWAT team is killed in the ensuing firefight. With Marvin's help, McClane reaches the massacre scene, rescuing Barnes and killing Stuart's men. Stuart retaliates by recalibrating the instrument landing system and then impersonating air traffic controllers to crash a British jet, killing all 230 passengers and crew on board. A U.S. Army Special Forces team led by Major Grant is called in. By listening in on a two-way radio that was dropped by one of Stuart's henchmen, McClane finds out that Esperanza, who's killed his captors and is now flying, is landing.
With Marvin's aid, McClane reaches the aircraft before Stuart's henchmen, but Esperanza traps him and the antagonists throw grenades into the cockpit. McClane escapes via the ejection seat mere seconds before the grenades detonate and the aircraft explodes. Barnes helps McClane locate the mercenaries' hideout and they tell Grant and his team to raid the location, but the mercenaries escape on snowmobiles. McClane pursues them, but the gun he picked up does not kill anyone when fired. He discovers that the gun is loaded with blanks, and he is horrified to discover that the mercenaries and most members of the Special Forces team have been in cahoots all along (one of the Special Forces is later killed by Major Grant when it transpires he was never part of the team and was merely a last minute replacement).
McClane contacts Lorenzo to intercept the Boeing 747 in which the mercenaries will escape; Lorenzo refuses to listen until McClane fires at him with the blank gun, thus proving his story. A suspicious Thornburg is monitoring airport radio traffic, and learns about the situation from a secret transmission to the circling planes from Barnes. He phones in a sensational and exaggerated take on what is happening, leading to panic and preventing the officers from reaching the escape plane. Holly subdues Thornburg with a stun gun.
McClane hitches a ride on a news helicopter that drops him off on the wing of the mercenary plane. He jams the left inboard aileron with his jacket, preventing the plane from taking off. Esperanza, who is flying the jet, is shocked when he sees McClane on the wing. Grant emerges and fights McClane, but the former is knocked off the wing and into an engine, which sucks him in, vaporizing him. Stuart then comes out and succeeds in knocking McClane off the plane. He removes McClane's jumper and re-enters the plane. However, he fails to realize McClane opened the fuel hatch before he fell off. McClane uses his cigarette lighter to ignite the trail of fuel, which destroys the jet, killing Stuart, Esperanza and all on board. The pilots of Holly's plane uses the fire trail to help them land, which the other passenger jets do as well. The passengers are safely evacuated and McClane and his wife are happily reunited. Lorenzo appears and thanks John.
Die Hard 2 was the first film to use digitally composited live-action footage with a traditional matte painting that had been photographed and scanned into a computer. It was used for the last scene, which took place on a runway.
One of the writers of the screenplay, Steven E. de Souza, later admitted in an interview for the book Action Speaks Louder: Violence, Spectacle, and the American Action Movie that the villains were based on America's "Central American" meddling, primarily the Iran–Contra affair.
General Esperanza's aircraft is a Fairchild C-123K Provider. This is a twin engine propeller aircraft modified to appear with four jet engines for the film. The pods for the J-85 jet booster engines are still visible under the wings between the mock-up jet engines.
The film exceeded all expectations by actually outdoing the massive box office success of Die Hard. The film had a budget of US$70 million and had a wide release in 2,507 theaters, making $21.7 million on its opening weekend. Die Hard 2 has domestically made $117.5 million and $239.5 million worldwide making it one of the most profitable Christmas films, almost doubling that of Die Hard.
On Rotten Tomatoes, the film has an approval rating of 69% based on 61 reviews, with an average rating of 6.1/10. The site's critical consensus reads, "It lacks the fresh thrills of its predecessor, but Die Hard 2 still works as an over-the-top – and reasonably taut – big-budget sequel, with plenty of set pieces to paper over the plot deficiencies". On review aggregator Metacritic, which assigns a weighted average rating to reviews, the film has a score of 67 out of 100, based on 17 critics, indicating "generally favorable reviews". Audiences polled by CinemaScore gave the film an average grade of "A" on an A+ to F scale.
Roger Ebert, who gave the original film a negative review, described the sequel as "terrific entertainment", despite noting the substantial credibility problems with the plot. Jay Boyar of the Orlando Sentinel dubbed the film as being as disappointing a sequel as Another 48 Hours and RoboCop 2 were and said about the film: "Whatever small pleasure there is to be found in this loud dud is due mostly to the residual good feelings from the first film... As played by Bruce Willis, McClane is still an engaging character, even if he is much less amusingly drawn this time. Willis is in there trying, but the qualities that helped to make his character sympathetic in the first film are missing. McClane no longer worries openly about his personal safety, as he did in the original movie. His quasi-cowboy personality from Die Hard is all but forgotten - he has become more of a Rambo and less of a Roy Rogers. And though the filmmakers try to establish McClane as resistant to advanced technology, this promising idea isn't developed."
Empire magazine rated the film three out of five stars, while stating "It's entertaining nonsense that doesn't quite manage to recapture the magic of the original. Still, there are some nice moments here, and Willis is on solid ground as the iconic McClane."
Gene Siskel ranked the film as the sixth best movie of 1990. Maxim magazine ranked the film's plane crash #2 on its list of "Greatest Movie Plane Crashes".