The Bonwit Teller department store in New York City is destroyed by a bomb during the morning commute. The NYC Police Department gets a call from "Simon" claiming responsibility. He threatens to detonate another unless suspended police officer John McClane is dropped in Harlem, wearing a sandwich board with a racial slur on it. They comply, and McClane is called in.
Zeus Carver, an electrician with a nearby shop, sees McClane wearing the board. He explains he is an officer on a case, but is soon attacked by a group of black men. They manage to escape in a taxi. At NYPD headquarters, they learn a large quantity of binary liquid explosives, like in the Bonwit explosion, were stolen recently. Now, Simon demands both McClane and Carver follow his instructions.
They have 30 minutes to solve a series of riddles, leading them to the Wall Street subway station to stop a bomb planted on a Brooklyn-bound 3 train. McClane boards it as Carver goes to answer Simon's call. Despite being on time and McClane locating the bomb, it detonates immediately after it is thrown off, derailing the train and damaging the station.
McClane and Carver regroup with the police, meeting FBI agents Bill Jarvis and Andy Cross, who explain that Simon is "Peter Krieg", a former colonel in the East German People's Army and a mercenary-for-hire. However, Krieg's real name is Simon Peter Gruber, the brother of Hans Gruber, who McClane had killed years earlier in Los Angeles.
Simon then calls the police, knowing the FBI is there, telling them about a bomb in a NYC public school with a radio detonator triggered by the use of FBI and police bands. Simon will give McClane and Carver the school location if they continue with his riddles, warning that evacuating any school will lead to detonation. While McClane and Carver do Simon's next task, all NYC's public works are organized to search schools, using 9-1-1 to coordinate. McClane realizes that Simon is using the school bomb to distract the police away from Wall Street. They return there to find that Simon's fake repair crews dug into the Federal Reserve Bank to steal $140 billion of gold bullion in dump trucks. They follow the trucks into an aqueduct in Tunnel No. 3. Carver continues Simon's game while McClane follows the trucks.
Within the tunnel, McClane kills some of Simon's men. A cofferdam is destroyed, flooding the tunnel, but McClane escapes through a vent, popping up near Carver. Surviving a car chase with Simon's men who had followed Carver, they find that each of the drivers had ten quarters. Realising the quarters would pay for a bridge toll, they head to a tanker vessel in Long Island Sound. They sneak aboard, learning that the bullion isn't there, and are captured by Simon and his crew.
Simon confirms the school bomb was a ploy to distract the police, before handcuffing them to the real bomb. He says he will destroy the tanker, redistributing the bullion across the Sound to destroy the world's economies. Before Simon leaves, McClane jokingly asks him for something for his hangover, much to his amusement. He happens to have a bottle of aspirin, tossing it to McClane. After Simon leaves, Carver frees their hands and they just escape before the bomb sinks the tanker.
As McClane and Carver are debriefed by the police, McClane reports that none of the bullion was on the tanker. He looks at the bottle of aspirin, seeing it came from a truckstop in Quebec on the Canada–U.S. border. McClane, Carver, and the police arrive at a warehouse near the truckstop where Simon and his men are in the process of distributing the bullion and planning their escape. The rest of Simon's men are captured, while Simon and Katya attempt to escape in a helicopter. McClane shoots an overhead power line that falls onto the helicopter, causing it to explode. After celebrating their triumph, Carver convinces McClane to call his estranged wife, Holly.
Bruce Willis as Lieutenant John McClane
Jeremy Irons as Simon Peter Gruber / Colonel Peter Krieg
Samuel L. Jackson as Zeus Carver
Graham Greene as Detective Joe Lambert
Colleen Camp as Detective Connie Kowalski
Larry Bryggman as Inspector Walter Cobb
Anthony Peck as Detective Ricky Walsh
Nick Wyman as Mathias Targo
Sam Phillips as Katya
Stephen Pearlman as Dr. Fred Schiller
Kevin Chamberlin as Bomb Squad Officer Charlie Weiss
Richard Russell Ramos as FBI Chief Hugh Prantera
Charles Dumas as FBI Agent Andy Cross
Michael Cristofer as CIA Agent Bill Jarvis
Additional cast members include Simon's goons: Richard Council as Otto, Mischa Hausserman as Mischa, Phil Theis as Erik, Robert Sedgwick as Rolf, Sven Torvaid as Karl, Timothy Adams as Gunther, Tony Halme as Roman, Greg Skrovic as Kurt, Bill Christ as Ivan, Gerrit Vooren as Nils and Willis Sparks as Klaus. Aldis Hodge and Michael Alexander Jackson appear as Raymond and Dexter respectively,