Former U.S. Army Ranger Mike Banning (Gerard Butler) is a Secret Service agent assigned to head the U.S. presidential detail, maintaining a personal, friendly relationship with President Benjamin Asher (Aaron Eckhart), First Lady Margaret (Ashley Judd), and their son Connor (Finley Jacobsen). On a snowy Christmas drive from Camp David to a campaign fundraiser, the car transporting the First Family spins out of control on an icy bridge. Banning pulls Asher from the vehicle, but fails to save Margaret as she falls to her death.
Eighteen months later, Banning works at the Treasury Department, having been removed from the presidential detail. During Asher’s meeting with South Korean Prime Minister Lee Tae-Woo (Keong Sim) at the White House, the Koreans for United Freedom (KUF), a North Korean terrorist group led by Kang Yeonsak (Rick Yune), mounts an air attack (with an AC-130 gunship) and hundreds of ground assault mercenaries to capture the building, killing most of the White House defending workforce. Aided by rogue members of the prime minister’s own detail, including former Secret Service agent-turned-private contractor Dave Forbes (Dylan McDermott), they hold Asher and several top officials hostage in the PEOC, where Lee is executed on live video. Before being killed, agent Roma (Cole Hauser) alerts Secret Service Director Lynne Jacobs (Angela Bassett) that “Olympus has fallen.” Banning joins the White House’s defenders during KUF’s initial assault. He falls back into the White House, disabling internal surveillance and gaining access to Asher’s satellite ear phone, which he uses to maintain contact with Jacobs and Speaker of the House Allan Trumbull (Morgan Freeman), now acting president, in the Pentagon’s emergency briefing room.
Kang uses Asher’s hostage status to force Trumbull to withdraw the Seventh Fleet and U.S. forces from the Korean Peninsula, thus removing American opposition of a third Korean War, and seeks to detonate the American nuclear arsenal, turning the United States into an irradiated wasteland in revenge for his mother’s death. To do this, he requires access codes to the Cerberus system, held only by Asher, Secretary of Defense Ruth McMillan (Melissa Leo), and Chairman of the Joint Chiefs Admiral Joseph Hoenig (James Ingersoll), all of whom are inside the PEOC. Asher orders McMillan and Hoenig to reveal their codes to save their lives, certain that he will not give up his own code.
Authorized to proceed, Banning’s first act is to save Connor, whom Kang plans to use to force Asher to reveal his Cerberus code. Banning finds Connor hiding in the building’s walls and sneaks him to safety. On reconnaissance, Banning kills several of the terrorists, including Forbes. Army Chief of Staff General Edward Clegg (Robert Forster) convinces Trumbull to order an aerial SEAL assault on the White House. The KUF discovers the assault force and activates the advanced Hydra 6 anti-aircraft system. Kang retaliates by executing Vice President Charlie Rodriguez (Phil Austin).
After Banning disables Kang’s communications, Kang tries to execute McMillan outside the White House in front of the media, but Banning rescues her. Banning takes out most of KUF as they retreat back to the bunker. With the KUF dwindling, Kang fakes his and Asher’s death by sacrificing several of his commandos and the remaining hostages in a helicopter explosion. Having two of the codes to Cerberus already, he eventually cracks Asher’s code using a brute-force attack and activates the system. As Kang and his remaining men in the KUF attempt to escape, Banning ambushes and kills all of them except Kang. After Asher is shot, Banning confronts and engages in hand-to-hand combat with Kang. Asher momentarily distracts Kang, causing Banning to kill him. After Asher informs him of Cerberus, Banning disables it with the assistance of Trumbull and his staff.
Banning escorts Asher out of the White House as the latter receives medical attention. Afterwards, Banning is reappointed to the head of the president’s security detail as Asher speaks to everyone of the aftermath of the attack.