Jack takes Henderson to CTU for questioning. Once there, he faces an unhappy reunion with his daughter, Kim. Mike appeals to Martha for help as Logan faces pressure from his Vice-President to declare martial law on L.A. Lynn connects the theft of his keycard to an impending strike on CTU, but his warning comes too late to stop a terrorist from infiltrating the building.

Jack takes his fight directly to the President as he attempts to force a confession from him that will prove his involvement in the day's events. Martha vents her hatred for her husband in front of the press as Logan gives a eulogy over Palmer's body. Jack and Audrey share a tender moment when it seems the crisis has subsided, but Jack finds that his problems have only begun as his past catches up with him.

Palmer, Mike and Lynne discuss various ways to dispose of the ticking bomb. They conclude that the desert is the best place to set it off. Jack determines that one man must pilot the plane carrying the bomb. He chooses to fly the plane himself and bids a tearful goodbye to his daughter. Tony and Michelle become suspicious of a Middle Eastern diplomat who is asking questions about the evidence against Syed Ali. Palmer departs for Los Angeles so he can be on hand when news of the nuclear bomb reaches the public.

Logan wrestles with his conscience when he learns that Martha is riding in the motorcade with the Suvarovs. Audrey convinces Curtis to take action as Lynn continues to abuse his authority. Jack learns that an ex CTU agent, Christopher Henderson, works for a company which is connected with the nerve gas.

Jack and Sherry Palmer prepare for a dangerous meeting with the head of the war conspiracy at the L.A. Coliseum; David Palmer sits in as the Cabinet waits for confirmation of the Cypress Chip's invalidity; the air strike on the Middle East draws nearer; the conspiracy goes to an old agent to put Palmer out of play.

Jack conceals himself inside the airport hanger and surveys the Russian separatists, feeding information to Curtis and his assault team. The terrorists begin executing hostages in an attempt to make Logan cave into their demands. Martha discovers that all traces of her conversation with Palmer may not have been erased.

Jack is captured by the terrorists, who use Derek as leverage to force him to compromise CTU's assault operation. Logan refuses to give into the terrorist demands as the time of the co-signing of the treaty draws near. Martha tries to tell her husband of the evidence she uncovered about her phone call with Palmer, but Walt interferes with her efforts. A new representative from District arrives at CTU and begins to undermine Buchanan's authority.

Jack interrogates Henderson's wife about her husband's connection to the terrorists. Lynn begs his sister to return his stolen keycard, while Tony regains consciousness and learns of Michelle's fate. Martha gives Logan the cold shoulder, while Curtis tracks another nerve gas attack to a local hospital.

Jack shows Heller the incriminating recording in the hopes that he will help them take down Logan, but Heller has plans of his own that will save face for the presidency. Miles tricks Chloe into leading CTU to Jack and Audrey. Mike and Martha both become more suspicious of Logan's actions, while Heller confronts the president with an ultimatum.

After stowing away aboard the flight containing Henderson's contact and the incriminating recording, Jack finds himself having to deal with a pilot who refuses to cooperate. Martha begins to break down, and Mike becomes suspicious of what she is hiding from him, while Logan tries to calm his financial backers.

As the missile speeds toward its destination, Mandy cuts a deal with Jack and the President to give up Marwan's location in exchange for a full pardon on all of her crimes. Tony and Michelle share a happy reunion, but Jack finds his relationship with Audrey shattered as she makes her feelings known. Logan's advisor suggests a drastic course of action when the Chinese government demands that Jack be handed over to them for trial. Palmer tries desperately to warn Jack of the danger against him. Jack's life changes forever as Tony, Michelle and Chloe help him to evade the trap set for him by Secret Service.

Jack and Chloe infiltrate Wayne Palmer's penthouse where David Palmer was assassinated, in the hopes of finding a clue to his murder. Jack convinces Wayne to cooperate and finds some information in Palmer's memoirs that leads him to the airport where the Russian president is about to land. CTU and Secret Service attempt to capture Jack, but they only find Chloe as Jack and Derek slip through their grasp. Martha tries to convince her husband that she received an important phone call from Palmer the night before his death, but a tape of their conversation seems to contradict her claims. Jack goes to the airport to find a lead, but a group of renegade Russian terrorists take hostages, including Derek, before he can act.

Jack contacts Mike and asks for a secret meeting in hopes of gathering evidence against Walt. Martha begs Aaron for help, while a desperate Walt tries to force Logan to aid him in his complicity with the terrorists. Buchanan butts heads with Lynn over a decision to violate the president's orders, while the Russians attempt to escape with the nerve gas.

Jack tracks down a man who has a connection to the terrorists. Logan is forced to grant him immunity in exchange for information on their whereabouts. Mike and Martha argue over Logan's public response to Walt's involvement with the Russians. Lynn is drawn away from his post by a personal crisis as the terrorists come closer to striking against the U.S.

Jack and Wayne locate a source inside Logan's administration who has information on Palmer's assassination. But things get complicated when they learn that Henderson is using leverage to keep her silent. Audrey is forced to choose between Chloe and Buchanan as Homeland Security begins to absorb CTU.

Jack captures Henderson and attempts to force him to hand over the recording, but Henderson targets Heller to buy himself more time. Logan confesses his involvement in Palmer's assassination to a distraught Martha. Miles traces Chloe to Buchanan's home, but Hayes finds herself questioning Logan's motives as CTU closes in.

Jack and Henderson wage an assault on the submarine as Bierko prepares to launch an attack against L.A. Chloe brings in someone from her past to aid her. Martha and Aaron enlist Mike's help in their plans to expose Logan.

While Jack has problems with Curtis, CTU discovers a nuclear threat and raids a terrorist warehouse, and a shocking explosion shakes LA.

With only four hours left, a rogue Jack Bauer stops at nothing to determine who is behind the day's most devastating events, and he uncovers an unexpected lead.

As the clock ticks toward the climactic series finale, three hours remain and a ruthless Jack Bauer is on an unwavering mission to uncover the truth, which only complicates circumstances for President Taylor as she prepares for a signing ceremony. Meanwhile, President Logan comes face-to-face with a formidable foe, and Chloe leads CTU on a high-stakes collision course with Jack Bauer.

The clock ticks toward the final seconds of Jack Bauer's most heroic day. As the world teeters on a terror plot of mass proportions, Jack and the team reunite one last time to avert an imminent international crisis. With little time left and the fate of the free world on the line, Jack is faced with an unthinkable and grave decision. Lives will be lost and the American administration will grapple with the day's most devastating news as the clock stops.

Mike pushes for the Vice-President to be sworn into office as the White House waits for news of Keeler's fate. Two innocent bystanders are dragged into the fight as Jack and Marwan both pursue a briefcase that contains the launch codes for America's nuclear arsenal.

After Logan authorizes Palmer to take charge of the crisis, Palmer sanctions Jack and Curtis to infiltrate the Chinese Embassy on a covert operation to capture a suspect. Tony and Michelle continue to bump into each other's personal lives, while Buchanan expresses anger at being kept out of the mission. Jack faces Audrey's wrath when a medical dilemma places Paul's life in jeopardy.

Jack finds that his efforts to bargain with Marwan for the location of the missile strike are futile. Heller pushes his son for information when CTU discovers that he may have had contact with Marwan before the attacks. Logan finds himself in the middle of a power struggle between Palmer and the ambitious Speaker of the House. Tony and Michelle explore their rekindled passion for each other, but their hopes for the future may be short-lived when a familiar player enters the game and takes a hostage.

Mandy uses Tony as leverage to try to force Michelle to aid in her escape. A Chinese security operative captures and interrogates one of the CTU agents involved in the raid on the embassy. Palmer and Logan argue over the option of evacuating all major cities that may be targets for the missile.