在Abu Fayed发动恐怖袭击的四年后，CTU被政府解散了。Jack Bauer在参议员Mayer所主审的参议听证会上被称使用了酷刑等非法手段来防止恐怖袭击。FBI在首席安全工程师Michele Latham被绑架后知道他们要入侵国家基础设施计算机。因为Jack曾与本次行动的策划者之一的Tony Almeida共事过，被传唤并要求他参与帮助这次的调查。而Latham被迫要给恐怖分子修理CIP装置。Jack和Renee审问一个和Tony有关的中间商时，那人被狙击手杀害了。

为了表明修补好的CIP装置可以进入国家电脑系统，Tony对航空中心实行了控制。总统Taylor和首相Matobo对派兵援助Sangala而进行磋商，第一先生Henry寻找与他儿子死因有关的线索。其间，一个FBI中的内奸帮助那名狙击狙击手逃脱了追捕。Jack和Walker探员跟踪着那个狙击手到快艇上，在那里逮捕了Tony。然而，CIP装置在此前被转到了Emerson一帮人的手中。

当Tony被FBI审问时，他暗中给Jack一个联系Bill Buchanan的电话。Bill Buchanan后证明Tony是卧底。他们和Chloe一起试图阻止一场涉及CIP装置在内的政府阴谋。Henry和他儿子的前女友Samatha见面。Colonel Dubaku拿到了CIP装置，威胁美国政府从Sangala撤军。为了让Tony继续做卧底,Jack在Chloe和Bill帮助下解除了Renee的武装，让Tony从FBI的手中逃跑。

As the threat of terrorism escalates, Jack Bauer is forced to take matters into his own hands to avert the imminent crisis facing the country. Meanwhile, lives are on the line as conflicted Agent Renee Walker copes with the volatile investigation, and FBI honcho Larry Moss is forced to keep a closer eye on his team as the nation's security is in jeopardy. At the White House, international stakes are raised and the First Gentleman proceeds with his personal mission.

As Dubaku presses President Taylor to comply with his devilish demands, she contemplates if the administration should negotiate to avert a disastrous terror attack. Meanwhile, away from the White House and the threatening international crisis, the determined First Gentleman struggles with his ongoing domestic mission, and perilous FBI Agent Walker diverts the attention of her tense colleagues. With national security on the line, Jack Bauer has a formidable plan in hopes of shielding the country in the “Day 7: 1:00-2:00 PM” episode.

As U.S. troops remain in position outside of Sangala, Dubaku seeks another high-value target using the CIP module. While the entire NSA scrambles to locate the breach, the situation rapidly escalates. Paranoid FBI Agent Janis Gold commands from her post, while Jack, Tony, Renee, Chloe and Buchanan follow leads.

As the country reels from the recent terror attacks and faces the mounting global ramifications, the administration refuses to acquiesce and presses on with their disapproval of the Juma regime. As Jack Bauer and team head to the White House for a pivotal meeting with President Taylor, Dubaku raises the stakes when he threatens the First Family

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

Jack and Renee Walker pursue Dubaku through the streets of Washington, D.C., with a little cyber help from Chloe. Meanwhile, the first family and the FBI are left reeling from incidents involving turncoat agents.

当总统和Mayer见面讨论取消对Jack的控诉时，Jack进入白宫试图从Burnett口中套出Juma即将开始的计划。Chloe从Dubaku的名单中删除了Burnett，以便让Jack有时间拷问他。但Janis发现Chloe删除了内容，Chloe被逮捕，特工组打断了Jack的审问。Jack被逮捕，Burnett拒绝了总统以豁免权交换Juma下一个目标的条件。其间，Dubaku在医院被暗杀了。Renee跟踪杀手到了一处位于Potomac河边的仓库。在那儿Juma的袭击部队准备乘船到他们的袭击目标。Renee偷偷上船时不小心把手机弄坏了。她发现Juma计划是从Potomac河中的下水管道入侵白宫。不过，她被Juma部队中的一个人发现了。在逃跑过程中试图及时预警白宫。

正当Juma开始袭击时，Renee被Larry所救并告诉了他有关Juma的计划。Jack被释放并帮助护送总统到安全屋。Bill发现Juma通过总统的手镯发信器确定总统的位置。他拿走了发信器引Juma到远离总统的地方，以便让Jack有足够的时间护送她到安全屋。Bill和白宫其他人员都被抓了。Jack和总统躲进了安全屋。特工队包围了Juma的部队。Juma恐吓说已经抓到了总统，迫使联邦特工撤退。副总统因害怕因为自己的命令让总统丧命而影响前途拒绝授权营救计划。Juma找到了Olivia并威胁要残害她迫使总统和Jack离开了安全屋。

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.

Malevolent mastermind Jonas Hodges emerges as Jack Bauer's latest adversary as the long, terrifying day ticks deeper into the night. Jack yields results from a surprise meeting, and the fight to avert additional terror attacks continues.

在港口，Jack和Tony审问一个港口警卫，知道了有一伙人来收集生化武器。Jack和Tony跟着他们来到了一个集装箱。在警卫将被他们杀害时Jack冒着被暴露的危险杀死了其中一员并和他们展开枪战。Jack抢来了装运生化武器的卡车，但Tony被抓。Larry发现有第三人来到Mayer房子的证据。Renee把Jack调查Starkwood的事情告诉了Larry。在白宫，Ethan因Olivia的威胁和为了承担Jack“杀害”了Mayer的责任而辞职。Henry结束了手术。Olivia把Ethan辞职的消息泄露给了媒体。Jack叫Larry派一个小队营救Tony并让他在Starkwood公司的人赶上自己前取回武器。Jack在运送的路上不得不停下修复毒气的泄露。这给了那伙人足够的时间追上了Jack并抢回毒气。Jack告诉Larry，Starkwood重新拿到了毒气而且自己可能被感染了。

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.

在从Starkwood撤离前，Larry殴打Seaton而成果转移了他们的注意力，让Tony在他们撤离时可以偷偷溜走并呆在Starkwood。Jack出现了相关症状并必须决定是否用他女儿Kim的干细胞来治疗他。Olivia威胁一名记者，让他不要把情况告诉公众。Tony在Starkwood线人Doug Knowles的帮助下知道了毒气的所在。此人曾经帮助议员Mayer参与Starkwood的调查活动。这促使总统Taylor下达派三架F-18战机空袭Starkwood。Knowles随后被抓到并带去Hodges那里。Hodges把他杀死了。Hodges知道了空袭并威胁要用导弹发射病原体要总统下令撤退。

总统和Hodges和Seaton会面，他们声称如果不加强Starkwood的军事力量就发射病原体。Tony秘密执行了一项总统Taylor不置可否的命令，他摧毁了装有病原体和导弹的建筑。这促使总统逮捕了Hodges和Seaton。Kim和Jack相聚。Larry和他的队伍看管了Starkwood，不过一个叫Galvez的工作人员带着一个毒气罐逃走了。在接下来的追逐和交火中，Larry被Starkwood的员工击伤。Tony背叛了Larry并杀了他。后Tony检查了毒气罐并命令Galvez把它带到安全的地方。

As the nation remains vulnerable, Jack Bauer endures the worsening pathogen pain. The FBI deals with recent deadly developments while matters involving key players takes this day into a unexpected direction.

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.

为了找到Jack，Chloe试图从Kim从机场拿到的手提电脑中找到Tony的位置。其间，Jack逃到一个车库试图开车逃跑，但Tony赶到后他企图自杀。最后Jack又被Tony抓住。在白宫，在Pierce的协助下，Ethan和Olivia见面。Ethan告诉Olivia她没有销毁录音带。Ethan要Olivia亲自把真相告诉她的母亲。Alan Wilson是整个事件的主谋并曾下令杀死Michelle等人。而Tony告诉Jack他一直想要给他的妻子报仇。当Wilson和Tony、Cara见面时，FBI及时出现。Cara和Wilson逃走了，Tony找到了他们并杀死了Cara。他在杀Wilson时说出了他杀死Wilson的另一个原因--Wilson杀死了Michelle连同他未出生的孩子。就在Tony对Wilson开枪时，Jack和Renee及时出现并阻止了他。Wilson被逮捕，但他否认对他的指控，使得Renee冒着离职的可能对他采取极端的措施以防止他脱罪。在白宫，Olivia告诉了她父母她参与杀害了Hodges。作为美国总统，Taylor决定她不能为女儿的罪行做掩护，这使她丈夫非常沮丧。Jack在向Gohar做祷告后，病情急剧恶化。Kim认为她不能让她父亲死，她自愿冒着生命危险捐出干细胞来拯救他父亲的生命。