When a burnt and mummified body of a missing and wanted person is found on a Marine base, in a furnace, NCIS must work with FBI. The burnt man turns out to be a serial killer. The both teams visit the man's family and discover something shocking. Also, the NCIS team must deal with the book McGee wrote about them, using "fictional" characters.

When a robotic vehicle named "Otto," a part of a high level project of the Department of Defense, causes a death of a Navy Lieutenant, and then later almost kills Abby, the NCIS team must find out who sabotaged the vehicle and murdered the Navy Lieutenant. Meanwhile, Ziva realizes that Tony keeps on visiting the hospital. What is he doing there?

After catching an international arms dealer, the NCIS team learns that Navy's highly classified weapons system will be sold to "La Grenouille," an important arms dealer. To stop the transaction, the team will send Ducky undercover. Meanwhile, another government agency appears to be working on the same case, with different plans.

Director Shepard makes a huge mistake by meeting a man alone to inform her about Le Grenouille, as their meeting turns into a murder of the informant. Now the NCIS team must gather all the existing info and try to finally hunt down their enemy.

When Jenny has to attend an overseas conference, Gibbs is made acting director, but he prefers to ignore his duties and lead the investigation of the murder of a man, who was found dead in a taxi headed to the NCIS headquarters.

When Jenny returns from her European trip, the entire NCIS team will be forced to take a Homeland Security polygraph test, and the deepest secrets of each agent are about to be revealed. Plus, an unarmed Tony and Jeanne are held hostage by a ruthless drug dealer.

The NCIS team uncovers a huge secret, as their mission to capture La Grenouille comes to an explosive and deadly conclusion.

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.

Secrets from Ducky's clandestine past come to the forefront after he's attacked at a crime scene. The team uncovers disturbing secrets from the good doctor's past.

Gibbs and the team must work with the shady Trent Kort to put away one of NCIS's most wanted.

After new evidence reveals that the Port-to-Port killer has infiltrated the agency, the NCIS teams chase every lead in a race to track him down.

The lives of NCIS members are in jeopardy when they come face-to-face with the infamous Port-to-Port killer, on the eighth season finale of NCIS.

The NCIS team, alongside the FBI and MI6, continue an international manhunt for an escaped British spy who has left one colleague fighting for their life in ICU.

NCIS, FBI and MI6 continue an international manhunt for an escaped British spy who is targeting current and former agents.