When one of their own is killed, the team must find the killer before they get to another member of the team, Gibbs. In an emotional investigation, the team tries to stay together, against the wishes of Assistant Director Vance.

When a former NCIS agent is found dead, the entire team is put in danger as they hunt after the killer.

Palmer is put in grave danger when he becomes the target of an anonymous murderer, whom only he can recognize.

While on an undercover mission, Ziva's life is put in grave danger when the serial killer she's been tracking becomes suspicious of her.

Two members of the NCIS team are sent to Baghdad to investigate a mortar attack that turned into murder.

The dead body of La Grenouille finally surfaces and the entire NCIS is put under the investigation by the FBI, with Jenny as the prime suspect for his murder.

When a dog owner is found murdered, the NCIS team must determine if his dog committed the murder or not, and Abby decides to fight for the dog's life by trusting her instinct about the dog's innocence. Meanwhile, Gibbs learns about Jenny's secret.

The NCIS team goes on a stakeout in a warehouse to catch a suspected thief of a high-tech naval radar, but they accidentally end up witnessing a murder. Meanwhile, Ducky hides a secret from the rest of the team.

After a young Muslim Marine is murdered near his Mosque, Ducky refuses to perform autopsy due to his religious beliefs, so the NCIS team tries to talk to the father of the deceased, and they send McGee to plant a bug in the Mosque, only to discover that the FBI ...

While trying to track down a delusional and violent Marine who thinks he's still in Iraq, the NCIS team will learn that the man has been the subject of a secret experiment - and it comes with a high price to pay.