Spoilers for this episode.
Security footage places Jack Bauer near the position used by David Palmer's assassin, turning a man officially believed dead into CTU's chief suspect. Audrey cannot accept that Jack would murder Palmer, while Buchanan has to follow the evidence. Jack and Chloe head into Wayne Palmer's heavily guarded building to search for something that could explain the killing. Derek remains with them, frightened by what he saw at the refinery.
Wayne initially believes Jack killed his brother. Jack hands over his weapon and appeals to their shared knowledge of Palmer, eventually gaining Wayne's help. An encrypted version of Palmer's memoir contains an inserted name and address that lead to Chevensky, a baggage handler at Ontario Airport. Their access to CTU's systems gives them away. Chloe is captured as Jack escapes with Derek and drives toward the airport.
At the presidential retreat, an altered recording undermines Martha's account of her conversation with Palmer. Cummings later reports to Nathanson that he changed it, exposing his involvement to the audience. Jack returns Derek to Diane, then confronts Chevensky, who takes poison during a diversion outside. Derek spots armed men approaching and runs back to warn Jack. The gunmen seize the terminal, taking Derek among their hostages while Jack remains out of sight.