(official recap from Fox's site)
Cromartie, disguised as Agent Kester, stands in the principal's office of John's school and demands a list of new students. The principal refuses and Kester snaps his neck. Kester sits at the computer and does the search himself.
Sarah leaves a message for a man named Sarkissian, asking about The Turk. In the kitchen, Derek places the T-888 memory chip on the table. Cameron lied about destroying it. Derek argues that Cameron cannot be trusted. John asks if the chip can be hacked.
Cameron admits to John that she lies to him when the mission requires it. They pick up a top of the line computer from a warehouse.
John sets up the computers and activates the chip. The monitor displays video of a woman in the video calls the T-888 "Vick" and he appears to have been married to her.
John continues to watch the video. One moment takes place at the woman's office, and then jumps to Vick reading their mail. John has an address.
Sarah and Derek break into the woman's house. She hasn't been there in some time. They find the computer missing and discover the woman is Barbara Chamberlain, City Manager of Los Angeles. She was in charge of the city's infrastructure.
Kester flashes his badge to the gym coach and goes looking for one of the new students on the list. The student doesn't match John Connor.
Sarah has been reading Barbara's files, but does not understand much. John finds a video where Vick is killing someone who appears to be Barbara in the woods. They head out to find her.
John and Derek find her body. When they roll the body over, it is not Barbara. Derek reads her driver's license, she's Jessica Peck.
John watches video of Barbara stating that Jessica was trying to stop Barbara's work. Jessica was a lobbyist trying to stop a program called ARTIE, or Automated Realtime Traffic Information Exchange. It would create a fiber optic network that would see and hear everything. The Turk might be the brain. Derek wants to destroy city hall. John says the best way is to create a virus so people think the program is bust.
Derek and John plan how to break into city hall. Derek tells her they are not going in the front door. They will be going underground to a series of tunnels.
At school, a student tells Cameron a cop is looking for John. Cameron stands outside the principal's and scans Kester -- he's a positive match for Cromartie. Cameron grabs Morris and sends him in to see Kester. Kester scans Morris, and leaves when it is not a match to John. She follows after Kester, and then John appears. She pulls him aside and leaves. Morris tells John everything that happened, and then John chases after her.
Barbara says she is almost finished her project and Vick encourages her. Cameron watches from the bed, and tries making conversation with John. John scolds her for putting Morris and danger and Cameron warns that it was Cromartie. Cameron tells him that he won't be back, and that she cannot tell Sarah.
John watches more video from Vick's chip. Vick was able to track down the Resistance fighters because they were following Barbara. Derek watches and realizes him men were sloppy. Sarah storms out, she's upset that they always find out about people too late. She doesn't want more people to die. John says the virus is ready.
Sarah and Derek walk through the tunnels below city hall. They blow a hole into the elevator bay using explosives and move to basement level 4 where the data center is. Sarah uploads John's virus to ARTIE, but suddenly it stops and alarms sound. The virus didn't complete. Guards chase after Derek and Sarah. When they corner Derek, Sarah jumps them from behind and they subdue the guards.
John continues looking over the video. Suddenly, John's cell phone begins looking for an internet connection. Cameron warns that Vick is trying to reactivate. John scrambles to shut everything down. Cameron says Vick was unable to do anything, and they need to be careful. Sarah and Derek return and tell John it failed. John realizes that there is another option.
Cameron lies on the bed. John takes a box cutter and cuts into her scalp to access her memory chip. John wants to use Cameron's chip to give her access to the ARTIE system, and she can stop it. John peels back her scalp and removes the chip.
Derek and John sit near a traffic light control box, John hacks away and helps Cameron's chip do what she needs to do. Cameron successfully shuts down the network. Derek grabs Cameron's chip and warns John that one day one of these machines will kill him.
Back home, John slides Cameron's chip back in. She reactivates.
Sarah tells Derek that Sarkissin returned his call about selling The Turk. Sarah knows Derek killed Andy and she threatens that if he ever lies to her again, she will kill him.
Sarah watches a final video from Vick's chip. He reaches into the shower, and kills Barbara.