When an Egyptian terrorism suspect "disappears" on a flight from Africa to Washington DC, his American wife and a CIA analyst find themselves caught up in a struggle to secure his release from a secret detention facility somewhere outside the US.

When the White House (Secret Service Code: "Olympus") is captured by a terrorist mastermind and the President is kidnapped, disgraced former Presidential guard Mike Banning finds himself trapped within the building. As the national security team scrambles to respond, they are forced to rely on Banning's inside knowledge to help retake the White House, save the President and avert an even bigger disaster.

Volatile CIA agent Carrie Mathison investigates and ultimately becomes obsessed with returned POW marine Nicholas Brody, who may or may not be an al-Qaeda-trained terrorist. Brody struggles to resume his domestic life with his wife and two children whom he barely knows. Saul tries his best to support his bipolar protégé while pursuing leads of his own and trying to hold his crumbling marriage together.

Set 18 months after season 7, the story arc involves Jack Bauer contending with assassination threats made during a peace conference between President of the United States Allison Taylor and President Omar Hassan of the fictional Islamic Republic of Kamistan (IRK). The season is set in New York City, with CTU's New York City Office having been re-activated,

Counter-terrorism agent Jack Bauer attempts to stop the assassination of United States Senator David Palmer on the day of the California presidential primary, while those spearheading the assassination plot stop at nothing to exact revenge on Bauer and Palmer.