Parsons gripes about his project; then a bomb explodes, killing the SecNav; Gibbs volunteers for a spec op, which takes him to Iran, where he runs into Parsons, and where they investigate. Tony tries to pursue Ziva in Israel. [Continued.]

Tony searches for Ziva in Israel and elsewhere; he finally finds her, but he returns without her. Gibbs, Fornell, and others work hard on the case of the bomber. McGee makes a huge discovery, which allows Gibbs to solve and to take a shot.

A bomb explodes in a Navy Lieutenant's apartment, killing his unfortunate building manager. The team must find the missing Lieutenant and identify the bomber minus McGee, who has lost his credentials.

Gibbs and company investigate the death of a woman with an ID card of a sergeant in the US Marine Corps; McGee finds that the real sergeant died in Afghanistan three years ago. Gibbs and McGee go to Kabul, sort things out, and do some good.

A Navy petty officer dies of a gunshot in a park in Baltimore, Maryland; Gibbs and company investigate; at the scene Tony sees a clue and a man. Abby finds links, then the gang put the pieces together and nail the shooter. Tony nods off.

An explosion and a fire damage an offshore drilling platform near the Virginia Capes, killing one (a major in the US Marine Corps Reserve) and injuring many others; Gibbs and company, along with Abby of the CGIS, investigate. The CEO and the chief legal counsel of the oil company assure the SecNav and Gibbs of their utmost cooperation. Tony and McGeek trace one lead, which appears to reach a dead end, but which leaves egg on McGoo's face; Gibbs and the other Abby suspect that the target was not the platform but rather the dead victim. Tony and McGee plus Gibbs and Borin revisit the dead end, where they make a major discovery; Abby puts things together in her shop; Borin questions the corporate lawyer in Gibbs's chat room and brings the investigation to a close. Meanwhile Halloween pranks abound, eventually tripping even Tony.

A Marine sergeant dies of gunfire during an alleged armed robbery; Gibbs and company investigate. Gibbs responds to a call for help for his dad; Tony and McGee take over; Abby provides an important fact.

At night at Quantico a hit-and-run driver kills a woman Navy petty officer; while investigating, Gibbs and company find a suspect, who has a solid but complicated alibi; the gang, a lawyer, and a local cop figure out the whole thing.

A security system detects a bug on the person of the SecNav; Tony contacts the NSA, where he finds a two-year-old paper describing such a breach; one man dies; the author helps the gang to nail the bad guys; Gibbs wants to keep her around.

A clown kills a Marine corporal; while investigating, Gibbs and company find Fornell, Diane, and her boyfriend, who says that he's someone else, and that he knows the clown. All the pieces come together, and the team bust the main bad guy.

Within 30 miles of Washington, DC, eight kids in Navy and Marine Corps families have suddenly become badly ill, requiring treatment in ERs and ICUs; Gibbs and company investigate; Carol, of the Naval Medical-research Center, joins the effort; immediately the number of sick kids grows to 14, then 19, 23, 28, and 34, and none of them responds to treatment. Duckie announces the first fatality, who was a veteran of Vietnam, then he describes the cause of death and the treatability in the kids. Abby says that she has misidentified the particular nature of the illness, so she, Jimmy, and Carol keep working, and they eventually nail it. Abby gives Jimmy a lecture about kindness, optimism, and parenthood. Then the gang identify an international traveler who in many places has recently encountered many kids and the fatality. Meanwhile Vance has three tense chats with his estranged father-in-law and then a nicer one.

A Navy petty officer dies of gunfire in a park in Washington, DC; Gibbs and company investigate; Hollis helps. The gang find an accessory for hire to a terrorist. An explosion kills six and injures 22, including Delilah. [Continued.]

In an effort to find the terrorist Parsa, Gibbs and the NCIS team track down one of his cohorts using evidence from the drone attack. Meanwhile, an emotionally shaken McGee struggles with the ramifications of the incident.

Ellie's gut says that Parsa is in his home district in NW Pakistan; there a SEAL team captures him alive. Gibbs, McGee, and Ellie fly to an aircraft carrier, where Gibbs and Ellie question him. Ellie gets into a bind, but Gibbs saves her.

An overturned van in Washington, DC, contains body armor, which Abby shows to be faulty and fatal; Gibbs and company find the body of the driver, then the source of the bad gear and the path to the troops in the Middle East. Justice wins.

When Tony seeks to question a man who appears to impersonate a Naval officer, the man draws a pistol; Tony kills him. The dead man proves to be a private investigator who had become involved in international intrigue. The gang sort it out.

Backstage before a charity-benefit concert in Washington, DC, an explosion kills a Navy petty officer first-class; Gibbs and company investigate; Abby fingers the bad guy, McGee finds out about him, and Gibbs and Ellie catch him at work.

In New Orleans, Louisiana, two local special agents of the NCIS, Pride and LaSalle, start to investigate the death of Dan McLane, who was not only a member of the US House of Representatives but also both a retired Naval Reserve commander and a retired agent of the NIS (before the NCIS); Dan had worked with Franks and had served as a mentor to both Pride and Gibbs; King Pride, a former partner of Gibbs, goes to Washington, DC, and spends time with Gibbs. Inter-agency intrigue begins; the FBI seizes control; a joint FBI-NCIS effort proceeds; Fornell joins the hunting party; the Gibbs team start producing results; King and Gibbs use an old-school technique; LaSalle in Nola says that he suddenly feels new respect for the Great Lakes office. An FBI agent in Nola dies in the same way as Dan; King goes back there, and Gibbs and Ellie go with him; Abby provides answers; the bunch in Nola follow the breadcrumbs left for them. [To be continued.]

While investigating the death of a US congressman, the Gibbs team and the gang in Nola continue to seek both a killer and a connection to an old case. Another man dies. Ducky suggests a theory, and the bunch put all the pieces together.

Delilah finds a clue, which may help to solve the alleged death of a US Navy lieutenant, Kit, two weeks ago in Budapest, Hungary; then her boss orders her that she has never seen it; however, she surreptitiously speaks with Tony, McGee, and Gibbs, who sends Tony and McGee to check for chinchillas and to find evidence. Then Tony and McGee meet a man who claims to be an agent of the CIA, who tells a wild story to Vance and Gibbs, and who asks them to back off; still, though, Vance tells Gibbs and Ellie to continue pushing quietly. Abby and Jimmy, interpreting the evidence from the chinchilla hunt, paint a picture of Kit, who appears to be alive. The director of the CIA backs out and leaves the case to the NCIS. Delilah finds that Kit has left breadcrumbs; Kit encounters Gibbs and Ellie, and Tony joins them. Kit provides illuminating answers, and the gang finish putting the pieces together, so Tony and McGee grab the bad guy, and McGee and Delilah give Kit a ride.

A distracted texting driver runs over the dead body of a Naval officer; Gibbs and company investigate; they find a connection to a previously unreported rape of a drugged victim. The team figure out everything, and they catch the bad guy.

During a court-martial of an Army first lieutenant, a Marine photojournalist disappears before he can testify; while Gibbs and company lend a hand, they find the body of the Marine, solve his murder and another one, and arrest two bad guys.

Tony goes to France to escort an admiral's daughter, Amanda, back to DC; meanwhile Gibbs and company investigate a death. Tony and Amanda run into trouble, work it out, find solutions for all seven executions, and report to the admiral.

The team must investigate a prison escape without Gibbs as he heads to Stillwater after his father's death.