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.

After eight hellacious hours of this terrible day have elapsed, the country remains on edge. President Taylor struggles with the painful circumstances facing the First Family, including her daughter Olivia (guest star Sprague Grayden). Meanwhile, a huffy Chloe faces-off against paranoid FBI Agent Janis Gold, while Jack and Agent Walker track leads through Washington, D.C. to eliminate the threat of another ruthless terror attack

Juma and his men take the White House by storm, killing most of the Secret Service and trapping Taylor and Jack in the saferoom. His efforts to extract her are thwarted until he is informed that the President's daughter is in the White House as well.

Renee and Larry try to convince Vice President Hayworth to let them rescue the President, but Hayworth will not budge until the FBI can produce proof that she is not in imminent danger.

The siege on the White House reaches an explosive end after Jack and Bill work together to try and save President Taylor.

Meanwhile, Jonas Hodges makes moves to cover his own tracks, starting with Ryan Burnett.

The game changes for Jack Bauer, and the FBI is forced to collaborate with other federal agencies. As the threat intensifies, the administration shakes things up and seeks a new perspective.

As the day stretches into the middle of the night, Jack and the FBI formulate a plan to prevent further terror attacks. Events take an unexpected turn when the politics surrounding the administration expand beyond the White House.

Jack Bauer endures the elements and fights on to prevent an attack that could change the country forever. As the catastrophic blow to the nation nears, Tony Almeida operates from the field and Kim Bauer, who was last seen in Season Five, returns. Meanwhile, the stakes are raised when the administration is faced with a blackmail scenario.

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

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.

Innocent lives remain in the line of fire as this terrifying day draws to a close. Jack is faced with an unthinkable situation while his perpetually imperiled daughter, Kim (guest star Cuthbert), gets involved. Meanwhile, the imminent threat stokes the heated rivalry between Chloe and Janis.

Jack Bauer is forced to help Tony escape from custody, only to find Tony plans to use Jack to reconstitute the pathogen. Aaron Pierce and Ethan Kanin work together and discover Olivia's role in Hodges' murder. Kim Bauer takes down her captors, and works with Renee Walker to find her father.

Presented with the evidence of Olivia's actions, President Allison Taylor is forced to make a decision between her family and the Presidency. Thanks to Kim Bauer, Janis, Renee and Chloe are able to save Jack and arrest Tony before he can kill Alan Wilson. With Wilson refusing to talk and Jack about to die, the fight is no longer in the field, it's for the hearts and souls of Jack and Renee.