Plot

John Cale (Channing Tatum) is a U.S. Capitol Police officer assigned to Speaker of the House Eli Raphelson (Richard Jenkins) after Cale saved Raphelson's nephew's life during a tour in Afghanistan. Cale is struggling to develop a better relationship with his daughter Emily (Joey King), who has a strong enthusiasm for politics. He hopes to impress her by getting a job with the Secret Service, but the interview is conducted by Carol Finnerty (Maggie Gyllenhaal), a former college acquaintance of his who believes that he is unqualified due to a lack of respect for authority and follow-through. After lying to Emily about the outcome of the interview, she and Cale join a tour of the White House. At the same time, U.S. President James Sawyer (Jamie Foxx) proposes a controversial peace treaty between allied countries to remove military forces from the Middle East.

Meanwhile, a man disguised as a janitor detonates a bomb at the center of the United States Capitol, destroying the building's dome. Raphelson, who was in the Capitol, is taken uninjured to an underground command center with Finnerty while Vice President Alvin Hammond (Michael Murphy) is taken aboard Air Force One. The White House is put on lockdown separating Cale from Emily (who had left the tour group to use the restroom). Meanwhile, mercenaries led by Emil Stenz (Jason Clarke) start killing off most of the Secret Service and take the tour group hostage, but Cale manages to take a gun and escapes a mercenary named Killick (Kevin Rankin) to go and find his daughter. Following protocol, retiring Head of the Presidential Detail Martin Walker (James Woods) escorts President Sawyer and his detail to the Presidential Emergency Operations Center. Once Sawyer gains access, Walker kills Sawyer's detail, revealing himself to be the real leader and his desire for revenge over his son who was killed in a botched black ops mission. Cale, who fails to find Emily, kills a mercenary and takes his gun and radio. Using the radio, Cale locates and rescues President Sawyer.

Walker and Stenz bring in Skip Tyler (Jimmi Simpson) to hack into the defense system, but they still require Sawyer to activate the nuclear football. Emily, while hiding, records a video of the mercenaries and uploads it to YouTube before eventually being captured by Killick. Walker demands $400 million from the Federal Reserve as ransom for the hostages. Cale and Sawyer manage to reach out to command which tells Cale to get Sawyer out through underground tunnels. At the command center, Finnerty uses Emily's video to discover the mercenaries' identities, discovering that they used to work for various government agencies and radical political groups. They are informed that Stenz, a former Special Forces operative, was disavowed and burned on mission, leading to his capture by the Taliban. They also discover that Walker has terminal cancer, suggesting his involvement to be a suicide mission and that the attack is not for ransom. Cale and Sawyer find the tunnel gate rigged with an explosive and are forced to escape with a presidential limousine. After giving chase with Stenz on the White House lawn, Cale and Sawyer are flipped into the White House pool after Cale gets distracted by Killick holding Emily at gunpoint. A gunfight erupts which results in an explosion that leaves Sawyer and Cale presumed dead. Hammond is then sworn in as President.

When Cale and Sawyer reveal they are still alive, they learn Hammond has approved an aerial incursion by Delta Force to take back the White House. Knowing the mercenaries have Javelin surface-to-air missiles, Cale tries but fails to stop the mercenaries from shooting down the helicopters. Cale gets into a fight with Stenz and ends up dropping his White House passes for himself and Emily while escaping. Having already learned of Emily from the video, Stenz, knowing that she is Cale's daughter, takes her to Walker in the Oval Office. Meanwhile, Tyler finishes the upload to NORAD and launches a missile at Air Force One, killing everyone on board, including Hammond. Raphelson is then sworn in as President and orders an air strike on the White House. Finnerty informs Cale of Raphelson's decision.

Walker tells Cale over the White House intercom to surrender Sawyer or he will kill Emily. Sawyer ultimately surrenders himself to save Emily, knowing Cale could still save them if he was free. Walker reveals to Sawyer that his motive for the attack was to convey a message of American power, and asks Sawyer to activate the nuclear football. However, Sawyer refuses to activate the football. When Walker threatens to kill Emily again, the alarms and sprinklers are set off by Cale setting various rooms on fire. In the chaos, Tyler tries to escape but encounters the tunnel gate bomb. When he tries to deactivate it, it detonates instead, killing him. Killick finds Cale and tries to kill him, but is ambushed by Donnie the White House tour guide (Nicolas Wright), who bludgeons Killick to death with a clock. After freeing the hostages and entrusting Donnie to get them out safely, Cale kills Stenz with a grenade belt. Sawyer attacks a distracted Walker, who ultimately gains the upper hand and uses Sawyer to activate the football before apparently shooting him dead. Using updated launch codes from an anonymous source, Walker targets various cities in Iran, but before he can initiate the launch, Cale kills Walker with a minigun mounted on a presidential escort vehicle. When Emily is told of the air strike, she takes a presidential flag and waves it on the front lawn and gets the jets to call off the attack. Meanwhile, Sawyer reveals himself to be alive since the bullet that hit him hit a pocket watch his wife (Garcelle Beauvais) had given him. Finnerty calls them to reveal that the mercenaries were not called in by Walker and that there is another person behind the attack. Cale realizes who it is and asks Sawyer for his help in exposing the person.

Later, Finnerty arrives at the White House with Raphelson. When Cale tells them Sawyer was killed. Raphelson then orders troops to be placed back into the Middle East. Cale then reveals Raphelson had conspired with Walker to orchestrate the attack because of Raphelson's opposition to Sawyer's treaty and proves it by having Finnerty call the call-back number on Walker's pager, which was the source of the updated launch codes. Sawyer then reveals himself and has Raphelson taken into custody, treating Raphelson's taking of the Presidency as a coup d'état. Sawyer then officially employs Cale into the Secret Service and takes him and Emily on an aerial tour of Washington, D.C. on his way to the hospital. As a result of the events, Russia, Iran, China, and other Middle Eastern and Asian countries agree with the peace treaty.