New York City police detective John McClane flies to Los Angeles, California, to visit his estranged wife, Holly, and their two children for Christmas. Argyle, an inexperienced limousine driver, picks John up at the airport and drives him to his wife’s office located on the thirtieth floor of Nakatomi Plaza. Uncertain whether Holly will invite him home that night, John enlists Argyle to wait for his call in the underground parking lot. At the lobby desk, he is disappointed to find his wife listed under her maiden name, “Holly Gennaro.” Riding the elevator to the thirtieth floor, John finds himself among revelers at the Nakatomi Corporation’s Christmas party. The President, Joe Takagi, recognizes him and leads him to Holly’s office, where they find her colleague, Harry Ellis, alone at her desk, snorting cocaine. When Holly returns, she is surprised to see John and shows him to the bathroom, where he washes up. Holly invites John to stay at the house and says she has missed him, but he confronts her about using her maiden name. Holly claims the Japanese businessmen prefer to think of a high-powered career woman as single. Holly is called away to make a speech, leaving John behind. Meanwhile, a group of international criminals led by a German man, Hans Gruber, park a truck in the underground parking lot and storm the building, killing two security guards and taking over the lobby desk. An African American computer expert, Theo, hacks into the security system to lock down the building, while John, who has taken off his shirt and shoes, calls Argyle from the bathroom and tells him to keep waiting in his limousine. The phone line goes dead, and John senses something is wrong. Armed with automatic weapons, Hans’s group emerges from the elevator onto the thirtieth floor and takes the partygoers hostage. Hearing shots fired, John pulls his gun and escapes to the emergency stairwell. Railing against the Takami Corporation’s greed, Hans leads Takagi at gunpoint to his office on another floor. There, Hans announces his plan to steal $640 million in bearer bonds stored in the company’s vault, but Takagi claims he cannot provide the necessary access codes. John spies some of the terrorists moving explosives into the building, then sneaks up on Takagi’s office as Hans shoots Takagi dead. After retreating to an unoccupied floor, John pulls a fire alarm, and although police respond, one of the terrorists posing as a security guard, Eddie, convinces the officers that it was a false alarm. Pinpointing the floor where the alarm was pulled, another terrorist, Tony, pursues John. Activating a table saw to lure Tony out, John ambushes the terrorist and the men struggle until they fall down a stairwell, where Tony dies from his injuries. Still barefoot, John tries to steal Tony’s shoes but they are too small. John sends Tony’s corpse down in the elevator to the thirtieth floor with the message, “Now I have a machine gun,” scrawled on Tony's shirt. Tony’s brother, Karl, intends to avenge Tony’s death, but Hans reminds him they must prioritize the robbery. John procures a CB radio and gains access to the roof, where he radios police. Although a policewoman reprimands him for using a secure line, she overhears loud noises as Karl and two of his cohorts shoot at John, and sends Sgt. Al Powell to investigate. Running back inside, John uses the strap of Tony’s machine gun to descend into a ventilation shaft, where he almost falls to his death but saves himself by grabbing onto the edge of an air duct and climbing inside. Sensing John might be inside the duct, Karl shoots at it from below but is drawn away when he learns Sgt. Al Powell is outside the building. John retreats to Takagi’s office where he smashes the window with a chair to get Al’s attention. Two more assassins, Heinrich and Marco, pursue him, but John shoots them both dead. In the lobby, Eddie opens the door for Al, who performs a cursory walk-through and leaves. Before Al drives away, however, John drops Marco’s corpse onto Al’s police car, prompting Al to call for back-up. Hearing Al’s distress call, television reporter Sam Thornberg begs for a news truck to cover the event. Over the CB radio, John tells Al that nine terrorists, led by Hans Gruber, remain, along with roughly thirty hostages on the thirtieth floor of the building. Deputy police chief Dwayne T. Robinson takes Al’s radio and orders John to stand by. Introducing herself as “Miss Gennaro” to Hans, Holly asks to move her pregnant assistant to a couch and requests bathroom breaks for the hostages. In the parking lot, Argyle hears news of the attack over his CB radio and realizes it is taking place above him. While continuing to penetrate the vault’s security system, Theo watches surveillance cameras and announces when four SWAT [Special Weapons and Tactics] members attempt to infiltrate the building’s main floor. As the terrorists fire shots outside, Robinson wants the SWAT members to retreat but their leader insists they keep going. The SWAT men are killed, and two terrorists, James and Alexander, launch a missile at an armored police vehicle when it approaches another corner. John sends an explosive device down the elevator shaft to the floor where James and Alexander operate their rocket launcher, causing a major blast. Police chief Robinson reprimands John over the radio, but John demands to speak to Al, who informs him that he just killed two more terrorists. Holly’s colleague, Harry Ellis, attempts to make a deal with Hans, lying that he and John are longtime friends. Hans gives Ellis his CB radio to contact John; although Ellis tells John that Hans will kill him if John does not produce a bag of detonators that Heinrich was carrying, John refuses, and Hans shoots Ellis. To stall the police, Hans offers a deal: if they release a list of incarcerated revolutionaries in Northern Ireland, Canada, and Sri Lanka, he will release the hostages to awaiting helicopters on the roof. Two FBI agents, “Big” Johnson and “Little” Johnson, arrive, informing Robinson that they are taking over. John comes across Hans, who fakes an American accent and pretends to be a Nakatomi employee, Bill Clay. Identifying himself as a policeman from New York, John enlists Hans’s help, giving him a handgun. However, when Hans points the gun at John and demands the detonators, Hans discovers the gun is not loaded. Terrorists Karl, Fritz, and Franco emerge from the elevator and John shoots them both dead as he retreats, cutting his foot on broken glass. As Karl and Hans return to the thirtieth floor, Holly notices Karl’s frustration and grins, sensing John is still alive. In a bathroom, John removes the glass from his bloodied foot and radios Al, asking him to pass along an apology to Holly in case he dies. He says he should have been more supportive when she was promoted; instead, he allowed her to move to California without him. He asks why Al is just a beat cop, and Al confesses that he accidentally shot a child while on duty. When the FBI cuts power to the building, the vault opens and the terrorists remove the bearer bonds. FBI agents lie to Hans that the prisoners have been released in exchange for the hostages and helicopters are on the way. At the McClane residence, Sam forces his way inside with a news crew to put John and Holly’s children, Lucy and John Jr., on the air. Hans sees the report and realizes Holly and John are married; thus, he takes Holly at gunpoint while the other hostages are ushered to the roof. John realizes Hans is planning to blow up the roof as the helicopters descend, and radios Al to warn him, but Al does not hear. Near the roof, Karl ambushes John and shoots him in the shoulder; however, John overpowers Karl, tying a chain around his neck and leaving him to hang. On the roof, John demands Holly, but the other hostages alert him that Hans took her to the vault. After John sends the hostages back inside, FBI agents in helicopters mistake John for a terrorist and shoot at him. He ties a fire hose around his waist and jumps over the side of the building, shooting through a window and swinging inside just before the hose snaps. As the terrorists’ explosives blow up the roof, John heads to the vault, where he and Hans come to a stand off. Hans holds Holly at gunpoint and forces John to drop his weapon. However, John removes a second gun secretly taped to his back and shoots Hans and Eddie. Hans totters backward and falls through a window, still holding onto Holly’s wrist. Just in time, John undoes Holly’s watch, and the two watch as Hans loses his grip and falls to his death. Reunited, John and Holly kiss. Outside the building, John embraces Al and introduces Holly using her maiden name, but Holly corrects him, identifying herself as “Holly McClane.” Covered in blood, Karl emerges from the building and points his gun at John, but Al shoots him dead before anyone else can react. Excited by the evening’s dramatic turn, Argyle drives his limousine out of the parking lot and picks up Holly and John.