While the newly-upgraded CTU is challenged by some unexpected and complicated circumstances, Jack Bauer becomes even more involved in preventing an upcoming assassination attempt on Omar Hassan, a visiting President. Meanwhile, international security is jeopardized by an explosive event, and Jack is reunited with agent Renee Walker.

Despite averting the assassination attempt on foreign peacekeeping leader Omar Hassan, Jack Bauer's day intensifies when he is forced to go further undercover to secure the unsecured enriched nuclear materials. As international delegates reconvene at the United Nations, President Taylor's goodwill comes into question and CTU races against time to assist with the mission.

As Jack's day enters the early morning hours, the nation remains vulnerable, and President Taylor presses on with her international peace process. With the possibility of colossal failure facing CTU, attention turns to who is to blame, and things get personal when operatives take matters into their own hands.

While Jack and Cole team up in the field to shield New York from the calamitous threat, a hostage situation has CTU completely stressed out. Meanwhile, unrelenting parole officer Prady presses on in his investigation, and unexpected developments send the Hassan family into a major tailspin.

As dawn breaks over New York, President Taylor endures a game-changing setback as the threat of mass destruction looms. Meanwhile, President Hassan makes a shocking decision that surprises his loved ones. But before long, trusted confidantes will become enemies of the state, and it's only the beginning of the betrayals that are to come as the race against time ticks over two pulse-pounding hours.

With only seven hours left in the series' final harrowing day, Jack Bauer sets out to avenge the tragic life-changing events that he has endured. As things become even more personal for Jack, he heads to CTU for an intense meeting after learning of a devastating development. Meanwhile, on the verge of achieving peace on a scale that has eluded the world for generations, President Taylor becomes deeply conflicted when former President Logan sits down at the bargaining table.

With only four hours left, a rogue Jack Bauer stops at nothing to determine who is behind the day's most devastating events, and he uncovers an unexpected lead.

The terror threat escalates as Jack heads for the U.S. Embassy with the CIA closing in on him. Meanwhile, Margot asserts her authority with unthinkable force; President Heller makes an impassioned speech to Parliament; and Kate takes matters into her own hands.