As Jack's day enters the early morning hours, the nation remains vulnerable, and President Taylor presses on with her international peace process. With the possibility of colossal failure facing CTU, attention turns to who is to blame, and things get personal when operatives take matters into their own hands.

Jack goes rogue to save a woman, and the White House needs a fall guy for Fayed's success.

A missing computer circuit board: the Russians get wind of Chinese espionage, the White House must find a leak, and CTU interrogates an unlikely witness.

While lives remain on the line, an emotional Chloe copes with the declining conditions. With only a few hours left in Jack Bauer’s day, the situation worsens when the politicking inside the White House corners the divided administration.

Undercover Agent Renee Walker confronts her painful past when attempting to broker a deal with a ruthless, but very well-connected German arms dealer. When CTU shifts its focus from the perilous circumstances surrounding Jack and Renee, lead analyst Dana Walsh comes up with a plan to quell her situation and Chloe O'Brian puts Arlo Glass in his place. As Jack and Renee’s undercover mission takes unexpected turns, the Hassan family turmoil has President Taylor reeling as the peace agreement is jeopardized.

As the terror threat continues, the Hassan family turmoil fans the flames of the increasingly urgent situation. When Jack closes in on a person of significant interest, a tense meeting between President Taylor and Omar Hassan takes an unexpected turn as the global security stakes are raised.

Jack finds himself confronting his father while the lead terrorist needs help if he's to explode the remaining bombs.

The Chinese want Jack to give them Russian nuclear technology, and the President wants the Vice President's resignation.

For the first time in New York City, Jack Bauer is reluctantly drawn into action as President Allison Taylor negotiates plans for international security with Middle Eastern leader Omar Hassan. As the 8th day keeps unfolding, we learn that CTU, now upgraded and operated by M.B.A.-schooled Brian Hastings, still has Chloe O'Brian, but also expert analyst Dana Walsh and systems analyst Arlo Glass.

Four explosive hours after being unwillingly drawn back into action, Jack Bauer reteams with a risky Renee Walker to track some very dangerous leads. Meanwhile, back at CTU, a desperate Dana Walsh faces tense and untimely circumstances, and emotions escalate when President Taylor learns of a larger looming threat that jeopardizes the peace accord with President Hassan.

Despite averting the assassination attempt on foreign peacekeeping leader Omar Hassan, Jack Bauer's day intensifies when he is forced to go further undercover to secure the unsecured enriched nuclear materials. As international delegates reconvene at the United Nations, President Taylor's goodwill comes into question and CTU races against time to assist with the mission.

Jack learns that one of the assassins, Alexis Mecir, is actually Victor Drazen's son and has become intimate with one of Palmer's aides. In an attempt to find the man ordering the assassinations, the aide agrees to plant a tracking device in Alexis' wallet. Back at the safe house, Teri and Kim discover their location is no longer secret or safe.

Against his family's wishes, Senator Palmer decides to go public about the secret scandal surrounding his family. Even as Alexis' brother, Andre, sends another assassin to the Bauer residence in hopes of finding Teri and Kim, a confused and scared Teri meets Dr. Parslow, a man who says they are good friends. Unaware of the danger Teri is in, he offers to give her a ride home.

Three years have passed since the events of Day Two. A van deposits a dead body outside the LA Health Unit. The body is infected with a deadly virus. Tony, now in charge of CTU, learns that this is a blackmail tactic to get the US government to release a drug lord, Ramon Salazar, whom Jack has just brought down, before Salazar's brother releases the virus into LA. Jack and his new partner, Chase Edmunds, prepare to sign a deal with Salazar at the prison. Salazar delivers a mysterious warning to Jack before killing his lawyer. Palmer is alive and well, and has returned to LA for the first time since the attack three years ago. He is running for re-election and is preparing for an important debate with a rival senator. He is accompanied by his brother, who happens to be his chief of staff and his doctor, who also happens to be his girlfriend. A young boy, Kyle Singer, is seen examining a large, mysterious bag of white powder. He plans to deliver it to some dealers later that day, but he is being watched by Salazar's men. Kim now works at CTU and has been dating Chase for three months. Kim wants to tell her father, but Jack has a mysterious health problem that may make things more complicated.

Jack and Chase quarrel over Chase's relationship with Kim. Meanwhile, they learn of a lead to the possible whereabouts of the virus after raiding a crack-house. Linda breaks up with Kyle when she learns that he is planning to make a drug delivery. Wayne approaches Palmer with information about his girlfriend that could damage his chances for re-election, while a CTU employee is not what he seems.

Marwan decides to trade Jack for Behrooz in hopes of distracting CTU from his real objective. Tony and Michelle weigh the consequences of the trade, while Curtis reluctantly interrogates Behrooz in order to learn more about Marwan.

Jack's search takes him to the home of an old enemy, while a bomber slips into the White House.

CTU's satellite tracking system is compromised as a bomb-carrying drone heads toward an unknown city. Meanwhile, US forces prepare for a nuclear retaliation on the Middle East.

Jack enlists the help of an autistic man in the search for Gredenko, and Sandra Palmer makes a fateful decision.

Russia presses the White House, while Jack must try to thwart the Chinese and his oldest antagonist simultaneously.

In order to prevent a war with Russia, the White House orders a trade of Jack's nephew for the circuit board, and puts Jack in custody so he cannot stop the exchange.

The nation remains vulnerable as Starkwood mastermind Jonas Hodges (guest star Jon Voight) remains at the epicenter of the mounting terrorist threat. Meanwhile, the FBI and the administration scramble to provide security and justice, and Jack Bauer questions a key suspect

President Taylor pressures CTU for progress while Jack's perilous plan has operatives panicked. As the scope of the looming threat expands, the dynamic at CTU changes and the ongoing crisis worsens.

With only six hours left, the clock races toward the series finale as President Allison Taylor faces impossible choices and much to the dismay of CTU, she enlists a private security firm to complete a sensitive task led by Mark Bledsoe. Meanwhile, Jack calls in a favor to his old friend Rick Vickers before he embarks upon a crucial mission of his own.

While Jack is questioned at the CTU, Teri and Kim are taken to the clinic to be examined. Meanwhile, certain he recognizes the name Jack Bauer, Palmer has Jack's background investigated. When he discovers that Jack was the sole survivor of a secret mission that he authorized two years ago, Palmer becomes convinced Jack is out for revenge and insists on talking to Jack face to face.