Over a year has passed since the events of Day One. President David Palmer is fishing with his son in Oregon when he learns of an emergency. He is taken to his underground bunker, where he learns that a Middle Eastern terrorist group known as Second Wave is planning to set off a nuclear bomb in Los Angeles
sometime that day.
At CTU, George Mason is ordered to contact Jack Bauer, who may be able to provide a lead to the terrorists.
Jack has been out of commission since the death of his wife. He is also estranged from his daughter Kim, who is now working as an au pair. He isn't interested in returning to work, but changes his mind when Palmer personally requests his help.
Kim overhears her boss abusing his wife, so she locks herself and their little girl in the bedroom. Gary forces his way in and attacks Megan.
A young girl named Marie is marrying a man who may have connections to the leader of the terrorist group.
At CTU, Jack learns that the key to finding the bomb rests with a group of American terrorists whom he infiltrated once before.