Buchanan asks Chloe to secretly look up Audrey's activities over the past year and whether or not she had any connection to Henderson and Cummings.
Buchanan takes Audrey into custody. Audrey says that Collette is lying about obtaining any information from her. When she asks for Jack, Buchanan tells her that Jack is the one who sanctioned this detention.
As Jack escorts Collette through CTU security, she confirms that she has met with Audrey and can identify her.
The torture tools are wheeled into Audrey's holding room. Buchanan argues with Karen and Miles about the extreme interrogation techniques they want to use on Audrey.
Jack enters and tells Karen that he will handle Audrey. She accuses Jack of always putting his feelings before work."Is that what happened with Nina Myers?" she asks. Jack warns Karen that Audrey's father, the Secretary of Defense, might have a problem with his daughter being tortured. Karen allows Jack to attempt to get Audrey to talk, but she will intervene if nothing comes out of it.
Outside the conference room, Buchanan confesses to Jack that he doesn't believe Audrey is guilty. Yet she might know something that can help their investigation.
Los Angeles Police happen upon a brawl in an alley, but it's a trap. Bierko and his men kill the cops and take their uniforms and weapons. They will use the police car to accompany the van with canisters in avoiding roadblocks.
Chloe finds a connection between Audrey and Cummings. The two had stayed in the same hotel room in Maryland, which was confirmed by the manager of the hotel. Jack is shocked at this revelation.
A techie named Shari Rothenberg reports to Chloe as Edgar's replacement. Shari sees Miles across the bullpen. They share a look.
Jack goes into the holding room and is abrupt with Audrey."I have nothing to do with these terrorists," she pleads. Jack shows her photos of Henderson and Cummings. Audrey says she only met Cummings a few times in Defense briefings. Jack brings up the hotel in Maryland, and he forces Audrey to admit that she slept with Cummings. She swears that she knows nothing else. Jack grabs her by the throat, and then stops. He turns to the security camera and yells to Karen that this is over.
"If you ask me, she broke him. Not the other way around," Karen tells Buchanan, as they watch the surveillance feed. Buchanan is certain that Audrey is innocent. Karen is not convinced, and she calls for Agent Burke to be brought in with his torture tools.
Chloe gives Shari an assignment, and Miles accuses Shari of not being qualified. Shari confesses to Chloe that she had filed a sexual harassment charge against Miles when they worked together a few years ago.
Buchanan tells Jack that Karen wants to use torture on Audrey, but Jack refuses to allow it. The guards try to stop him, and Burke is forced to taser Jack. The guards take Audrey away as Jack is put in handcuffs.
One of the snipers chasing Wayne Palmer calls Henderson. Henderson orders the man to find the missing Wayne and kill him.
Agent Pierce repeatedly tries Wayne's cell phone but keeps getting his voice mail. A fellow Secret Service agent tells Pierce that Wayne cleared through a checkpoint half an hour ago. Pierce wants to go look for Wayne, and asks the agent to keep it quiet.
Jack insists to Karen that Audrey is innocent. He thinks Henderson gave Collette Audrey's name in order to mess with Jack. They are wasting time when they should be interrogating Collette, who has immunity. Jack wants to get Collette to admit that she is withholding information, which will negate her immunity deal. He begs Karen to let him and Chloe try to find something to impugn Collette.
Miles tries to catch Shari breaking protocol, but Chloe steps in and accepts responsibility for her underling's actions. Miles accuses Shari of lying about the sexual harassment charge. Chloe stands up to him, saying that their main focus is to find the nerve gas. She threatens to file a complaint if he interrupts their work again.
Jack asks Chloe to help him save Audrey. He needs evidence that Henderson and Collette had direct contact.
Both Bierko's van and the cop car pull up to the Wilshire Gas Company. The terrorists shoot the guard at the gate and start unloading their canisters. Bierko finds the manager in charge. He makes the man escort them to the control room as the canisters are brought to the distribution tank.
Bierko instructs the manager to reduce the pressure in the pipes so that the substance they are going to add will not become inert. The man is in fear of being killed by Bierko.
Pierce enters the woods. Wayne orders him to drop his gun, but then realizes it is Pierce. The two run from the gunmen after Wayne.
Burke administers a drug into Audrey's veins, but she cries that she doesn't know anything. Meanwhile, Chloe finds that Henderson placed eight calls to Collette's cell. Jack tells Buchanan that this news means Collette's immunity is voided. He wants him to get the President to null the agreement. He also demands that no more harm be done to Audrey.
Jack runs into Collette's holding room. He accuses her of withholding information about Henderson. The Federal Marshal guarding Collette says that Jack can't question her until the order to rescind the immunity is sent. Jack knocks the Marshal out and trains the man's gun on Collette. Collette admits that Henderson told her to use Audrey's name. Jack threatens to kill her unless she tells him what was inside the schematic. Collette says that it is a natural gas distribution center. She doesn't know which one.
Jack tells Buchanan the new information. This is how Bierko is going to deliver the Sentox into people's homes. Jack gives the Marshal's gun back to Buchanan.
Jack bursts into the holding room and orders Burke to stop torturing Audrey. Jack tells Audrey that Henderson set her up to get at him. Jack apologizes and takes her in his arms."I knew you would come," Audrey says in tears. Jack kisses her.
Chloe brings up all the city's gas centers. Buchanan thinks they only have fifteen minutes before detonation, and Jack heads to field ops to prepare to leave.
Shari tells Buchanan that she was a Chemistry major and knows that the pressure index of the natural gas would have to be reduced in order to keep toxins from becoming losing their effectiveness. Chloe pulls up PSI levels at the Los Angeles distribution centers and finds that the Wilshire Gas Company's has just dropped. Buchanan quickly leaves to let Jack know. Shari notes that Buchanan's hand brushed against her shoulder and that this is wrong. Chloe squirms quietly.
Pierce and Wayne make their way past his flipped car. Suddenly, a missile wheezes past them. Wayne is knocked down. Pierce returns fire into the darkness at the gunmen. He puts Wayne into his car and they escape.
Jack, Curtis and the TAC team fly in the chopper to the Wilshire Gas Company. Chloe radios that the main control room is where the PSI level is adjusted. Meanwhile, Bierko's men set remotes on the canisters.
Chloe scans heat signatures outside the site, and finds the pilot a landing spot away from the two men patrolling the perimeter.
Jack and the TAC team rappel down to the roof of the gas plant from the hovering chopper.
Jack and Curtis make their way into the building and take out two of Bierko's men with silenced guns.
Jack and the CTU team sneak to the control room. One of the terrorists sees them and warns Bierko, who shoots. Amid the gunfire, Bierko activates his remote and the canisters start to emit gas into the tank. Jack goes after Bierko but stops when he notices the canisters in the tank. The plant manager says that it is too late to shut power because the gas will already spread. He tells Jack that the pipeline that feeds into the tank is outside. Jack notifies CTU that he intends to ignite the natural gas that has mixed with the Sentox. He can incinerate the mixture before it leaves the plant. Curtis and the rest of the team evacuate.
Jack places the explosive on the pipe and sets the charger to blast in 30 seconds. He runs out as the explosions burst the pipe, sending flames into the air behind him.
Jack makes it outside, but sees Bierko fleeing. He heads back in and calls to Bierko. Bierko is slammed against the stolen cop car when a flame erupts at his back. Jack goes to pick Bierko up, and the man fights back. They throw punches at each other. The main tank explodes as Jack pulls Bierko into the car. A wave of flame blows out the car windows.