The Fourth Season of 'NCIS: Los Angeles' finds the unit in crisis, with team leader Callen (Chris O'Donnell) accused of murdering a suspect in cold blood. The danger mounts as operations manager Hetty Lange (Linda Hunt) faces threats from her past. The team endures, only to uncover a secret that could jeopardise the people closest to former Navy Seal Sam Hanna (LL Cool J). In a crisis-level case, the team crosses paths with the mobilised crime-solving unit and allies with them to track down a terrorist. With the ace field work of Special Agent Kensi Blye (Daniela Ruah) and LAPD liaison Marty Deeks (Eric Christian Olsen), along with the brilliance of tech specialists Eric Beale (Barrett Foa) and Nell Jones (Renee Felice Smith), no evidence escapes scrutiny. In the war against crime, intelligence is the greatest weapon - and the sinister perpetrators inhabiting the City of Angels are no match for the skilled NCIS: Los Angeles team!