Jack, Audrey, Kim, Chloe and Barry wait in the sealed conference room. Buchanan is protected in his office, as is Tony in medical. They are saddened to see their dead co-workers in the other offices.
Buchanan calls Curtis, who is on his way back from the hospital with the chemical response team. It may take thirty minutes to get the team to CTU.
Buchanan calls the conference room and lets Jack know that he can find Henderson by pulling up a building grid. All of CTU's gas masks and Atropine medication are in contaminated areas.
Chloe is in a state of shock. Jack needs her to work, but Chloe can't move. Barry, who is a clinical psychologist, thinks he can help her. Barry pulls Chloe away from the window facing Edgar's body and tries to steady her nerves.
McGill, who is sealed in the holding cell, confesses to the guard watching him that the nerve gas being released was his fault. "I didn't want anyone to know I got beat up," he sighs. "So we're all gonna die because you got embarrassed?" the guard asks incredulously.
Tony gets up from his hospital bed and sees the dead bodies outside the medical area.
Jack calls down to the medical unit. The doctor tells Jack that Agent Burke got Henderson secured in time. Tony hears that Henderson is in there with him, and he knocks the doctor unconscious. Tony hangs up on Jack.
Tony sees Henderson lying groggily on a bed and he grabs Burke's gun. On the video feed, Jack sees Tony holding Burke at gunpoint. Tony wakes Henderson and blames him for taking Michelle's life. With tears streaming down his cheek, Tony threatens to kill him. Jack tries to calm Tony down over the intercom. He can sympathize because he lost Teri in the same way. They need Henderson to save thousands of lives. Tony understands and backs off.
Burke continues injecting Henderson with the pain-inflicting hyoscine-pentothal. Despite this, Henderson refuses to say anything about Bierko or his computer password.
Logan and Vice President Gardner grill Karen Hayes over the phone about the hit on CTU. Karen is a high-ranking official in the Homeland Security office in Los Angeles. Karen suggests an emergency restructuring that would put Homeland Security in charge of finding the terrorists over CTU. Gardner gives her approval.
Gardner presses the President to enact martial law because it is the effective solution, but Logan insists that his advisors believe it will only create mayhem. Gardner notes that, with only military personnel on the streets, the terrorists would not be able to move freely. Logan is indecisive.
Bierko instructs his operative to move all of the nerve gas to the new target.
Jack pushes Barry aside and pleads with Chloe to help decrypt the files from Henderson's computer. She doesn't want to. "We do not quit until it's over," Jack presses. Barry interjects that Jack is only making it worse. He then accuses Jack of never being there for others when they need it the most. Jack angrily walks over to Barry and grabs him by the throat. Jack reproaches him for taking advantage of Kim. Kim steps in and explains that Barry helped her deal with suicidal thoughts. Chloe breaks the tension in the room by announcing that she will get back to work.
Suddenly, an alarm beeps. Chloe discovers that the seals on the protected rooms are breaking down. The nerve gas must have been laced with a corrosive acid that is eroding the partition seals. She thinks they have about twenty minutes before the gas permeates the isolated zones.
Martha overhears Novick defend himself to Gardner about usurping his position. She is surprised that her husband is allowing Gardner to create policy. Martha knows that Gardner wants Logan to fumble so that he can assume the Presidency. Novick begs her to intervene, alluding to past events where Gardner took credit for success and left Logan out to dry on failures.
Buchanan warns all workers in the protected areas that the nerve gas is eating away at the seals. They need to figure out a way to flush the gas out of the contaminated zones.
Jack confides to Audrey that he persuaded Kim to stay at CTU for his own benefit. It will be his fault if something happens to her.
Chloe thinks that she may be able to flush out the contaminated areas with air conditioning. Yet she is being blocked by a program set up on another computer that she cannot access from a remote. Jack wants to go behind the cleared wall of the conference room to get to that computer. He will have to hold his breath when entering the ventilation room where the computer is. Jack pulls off one of the wall panels and climbs inside. They replace the panel once he is in.
Jack shimmies his way along the crawlspace and reaches a storage area. He tapes over the door he entered through to create an airlock to the conference room.
Jack radios Chloe to say that he is about to head into the ventilation room. He says he will tap his comm unit three times when he is back inside the safe room. Jack pulls up his jacket hood and sucks in one last big breath.
Jack steps over the dead bodies in the hallway. He removes another wall panel to discover iron bars blocking his entrance to the ventilation room. Jack can see the computer running the program that Chloe referred to. He hurries back to the storage area.
Back in the conference room, Chloe sees that the seal corrosion is now rapidly increasing. Kim nervously asks if they can do anything to help Jack. Chloe quickly shoots her down and they argue. The three taps from Jack echoes on the radio when he arrives in the storage room. He waits twenty seconds for the room to clear of any residual gas. As Chloe monitors the storage room's air, they all wonder aloud what Jack's quick return means.
After the twenty seconds, Audrey gives Jack the signal to breathe. He tells them that he was unable to get to the computer because of a security grate but he did see the program running. Chloe learns that the grate was a new addition that someone neglected to file properly. The only way to enter the ventilation area is through the holding room where McGill is being kept.
Jack calls McGill and explains the situation. He is the only one alive who can get to the computer. Unfortunately, there is no way to airlock the holding room once he has exited it. This means that both he and the guard will die. McGill rationalizes to the anxious guard that they have no other choice. McGill tells Jack that he will do it.
Kim apologizes to Chloe for snapping at her. She asks if Chloe had contact with Jack while he was gone. Chloe admits that she sent him information about Kim's life -- including her breakup with Chase and her depression.
Jack returns to the conference room and he has Chloe pull up the feed to the holding room.
McGill watches as the guard says goodbye over the phone to his child. McGill lets Chloe know that he is ready. McGill takes a deep breath and opens the door. He runs upstairs and turns off the program on the computer. McGill runs back out.
When the air conditioning finally responds, Chloe starts the vents. Although the air won't be clear for another fifteen minutes, this will help slow down the rotting of the seals.
McGill returns to the holding room and shuts the door behind him. He and the guard hear Jack thank them over the intercom.
The guard exhales and is relieved. "I'm okay," he exclaims. Two seconds later, he convulses and keels over. McGill gasps for air and dies too. Jack and the others watch this helplessly from the conference room.
Jack orders the medical room's security feed pulled up. He sees Burke prepare another syringe as Henderson still refuses to confess. "You're wasting your time," Tony says bluntly.
Jack asks Chloe to keep working on hacking into Henderson's computer because the seasoned former agent will divulge nothing. Jack asks Kim to stay when the gas is exhumed because they still need to talk. She says that she loves him but doesn't want to be around him. "Every time I am, something horrible happens. People die," she adds. Jack is heartbroken and he begs to spend a little time with her. She refuses, and goes to Barry's waiting arms. Audrey takes Jack's hand in comfort.
Novick and Martha review the press statement that Gardner has drawn up. Logan stands behind what it says. Novick leaves the room, dejected.
Martha tells her husband that she will support his decision but that she won't stand by and watch Gardner promote his own agenda. Logan breaks down to her. "I don't know how much more of this I can take," he says, referring to Palmer's assassination, the hostages and the nerve gas. "I almost lost you," he cries. Martha assures him that she is still here with him.
Bierko phones a European woman named Collette Stenger and asks for the high-security schematics he is paying her for. She says she is not ready and hangs up on him.
Collette returns to bed with her lover, Theo Stoller, without telling him what she is working on.
Karen Hayes calls Buchanan to inform him that she is heading to CTU with a team. System analyst Miles Papazian sits beside her in the car. He informs his boss Karen that he has re-formatted CTU servers to Homeland Security specs and routed their tactical protocols through him. Karen gives him authority to replace CTU personnel with some of his own because they won't be in any shape to continue working. She explains that Buchanan will no longer be in charge and that CTU ceases to be an operational entity. All the people there will now report to the two of them.
The sealed doors raise on the CTU contained offices as the nerve gas is stripped out by the air conditioners. Jack says goodbye to Kim before heading out. Jack orders Barry to take her out of Los Angeles.
Henderson's nervous system shuts down. When Jack calls the medical room, Tony tells him that Henderson is in a coma. "You've had your chance, he's mine now," Tony says, clutching the gun. As he runs through the halls toward the medical unit, Jack urges Tony not to do anything to Henderson because it won't make him feel better about losing Michelle. Tony ignores his plea with renewed determination.
Tony knocks out Burke. He prepares a syringe and holds it over Henderson, but Tony can't kill him. Suddenly, Henderson awakes and grabs Tony's wrist. He forces Tony to stab himself in the chest. Tony's face goes white and he falls to the floor. Henderson gets up off the table and grabs the gun. Although he is weakened, he runs out.
Jack enters the clinic and finds Tony and Burke on the ground. Gasping his last breath of life, Tony tells Jack that he couldn't do it. Jack clutches Tony's head. Tony dies, and Jack cries with him still in his arms.