24 Season 2 is set 18 months after Season 1. The main plot follows the work of now-President David Palmer and agent Jack Bauer to stop terrorists from detonating a nuclear bomb in Los Angeles. Introduced into the situation is Kate Warner, a woman who ends up getting vital information related to CTU's mission.
In the second act, the leader of the terrorist cell is found and Jack must force them to reveal the whereabouts of the bomb, and stop its detonation. In the final act, Jack, Kate, and CTU try to prevent a misdirected retaliatory strike from the U.S. by exposing the real masterminds who let the terrorists acquire the bomb.