The cabinet debates invoking the 25th Amendment to remove David Palmer from office. Jack Bauer finally gets a hold of the chip, but it has been damaged. When Bauer follows up on his next lead, he discovers Sherry Palmer is involved in the threat.
Jack and Chase allow Amador to escape, hoping that he will lead them to the man behind the virus attack. Sherry blackmails President Palmer and forces him to support her alibi during the time of Milliken's death. Michelle deals with mass hysteria at the hotel.
The nuclear warhead is launched from Iowa via a cruise missile. Marwan escapes. Edgar uncovers incriminating evidence against Richard Heller. Tony and Michelle decide to give their relationship another try, but their hopes for the future are put at risk when Mandy enters the game and takes Tony hostage.
Jack, Chloe, Bill, and Karen realize that the recording was erased by Miles. However, CTU is soon forced to switch tracks and focus on a new threat: Bierko escaped, and he plans to seize another powerful weapon. With the new threat quickly approaching, Jack must use Christopher Henderson in a delicate sting operation. Meanwhile, the drama at the retreat turns deadly.
Jack seeks Bill's help to retrieve Josh. Phillip's men obtain Josh without living up to their end of the bargain. The situation at the White House becomes increasingly tense as Karen Hayes is arrested for covertly helping Jack, and Milo's brother reveals to Nadia just how much Milo cared for her.
Jonas Hodges prepares to enter witness protection, even as Olivia Taylor sets in motion a plan to eliminate him. Jack and Renee attempt to track down Jibraan Al-Zarian, the innocent man whom Tony plans to set up as a scapegoat for an impending terrorist attack.
CTU New York struggles after its systems are destroyed in the aftermath of the EMP explosion, forcing Chloe O'Brian to take drastic actions to get it back up and running. Jack Bauer and three CTU agents are pinned down by sniper fire and are unable to radio for backup. Kayla Hassan is finally reunited with her parents.