CBS

Season 5: Episode 6 - Big Brother

Big Brother: When a joint CIA/FBI/NCIS task force is ambushed during an operation, NCIS: LA is called in to investigate and Eric quickly discovers that the CIA and FBI computers have been hacked. Using the hacker’s signal, the team locates the person responsible – a 15 year-old prep school girl. Callen goes undercover as a substitute teacher, and the suicide of a blackmailed teacher demonstrates the consequences of the hacking. Looking through the girl’s social network friends leads NCIS to a suspect and Eric uncovers when and how the suspect successfully gained access to the systems. Using the girl as bait, the team takes down the hacker. Meanwhile, Deeks brags about his new "walking workstation” and Eric connects with the school girl.