This time, another day begins for Jack Bauer as bioterrorists are attempting to release viral capsules into Los Angeles and eventually throughout the United States. President Palmer must deal with a scandal as he seeks re-election against a Republican senator, John Keeler. Jack is again thrust into action as he tries to tie Ramon Salazar to the viral threat; however, presumed-dead Operation Nightfall operative Stephen Saunders turns out to be the mastermind behind the release of the Cordilla virus.