Mike manages to find Connor, and gets him out the White House to safety.
Meanwhile Kang has held a knife to the throat of the Admiral, and then beaten up the Secretary of Defense until they gave up their Cerberos codes - to de-arm the nukes. The President is hoping to hold out so he doesn't give up the last passcode.
Forbes, the traitor, is sent out the bunker to find Banning, and then does the Die Hard homage thing of pretending to be lost and confused, only soon enough to say something that gives him up -- he knows the name of the terrorist leader. They fight but Banning gets the better of him. To redeem himself, Forbes radios to his leader to tell them that he got Banning.
Banning cuts the video feed from the bunker, forcing Kang to attempt a public execution on the steps leading up to the White House with the Secretary of Defense. Mike shows up again and takes out more of the bad guys, allowing the Secretary to run to safety.
Kang gets back to the bunker. He chains the prisoners together and makes them wear black hoods, then leads them out to the front lawn. They get into a chopper, but as it takes off, one of the terrorists detonates his suicide vest, killing everyone on board. The nation assumes that the President is dead.
Kang though, is back in the bunker with the President and still a few more bad guys, somehow. His hacker lady breaks the last Cerberos code, and they plan to detonate all nukes in their underground bunkers, destroying large parts of America. They start the 5 minute countdown, then blow a hole through the bunker and start their escape.
Banning shows up, and takes out Kang's remaining henchmen. The President fights back, but is shot in the chest. Banning and Kang face-off, until Banning manages to pull a few secret-service maneouvers and keeps his promise to stab the bad guy in the head. He patches up the President, then runs back to the bunker and with a little help from the war-room tech guys he manages to disable the self-destruct with seconds remaining.
Later, at a press conference, the President vows that this will only make the country stronger, and we see that Mike is back on his security detail, where he belongs.