After four years off the grid, Jack is apprehended in London by the CIA – on the very day that President James Heller arrives. As the President faces political pressure over a US drone program run from a UK-based base, only disgraced agent Kate Morgan suspects that Jack's capture was all too easy.

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.

An unlikely duo joins forces to forestall an impending attack. The terrorist reveals her demands. The President orders a military lockdown, but it may be too late.

Jack and Kate race to save the life of a player tied to the terror threat; Jordan faces a perilous mission; President Heller engages Margot to put an end to her attacks.

Jack Bauer's harrowing day crescendos as he pursues final leads at all costs. The emotional toll of the day's events escalates when Kate Morgan learns the truth about her husband and Audrey confronts Boudreau about his duplicity. Making matters incredibly worse, the scope of the terror threat widens and the potential devastation reaches new heights.

The clock ticks toward the final seconds of Jack Bauer's most heroic day. As the world teeters on a terror plot of mass proportions, Jack and the team reunite one last time to avert an imminent international crisis. With little time left and the fate of the free world on the line, Jack is faced with an unthinkable and grave decision. Lives will be lost and the American administration will grapple with the day's most devastating news as the clock stops.