Aboard Air Force One a Naval officer dies after eating with the Potus, then a Marine officer (connected with AF1) also dies in Georgetown in the same way. Abby identifies the cause, and Gibbs thwarts an attempt to assassinate the PotUS.

US Navy commander "Seadog" washes up dead on a North Virginia beach. 2 dead, alleged drug dealers are found nearby. All 3 are shot. NCIS, joined by DEA and FBI, investigate.

A Marine colonel disappears during an ambush in Iraq, as does $2M in cash; he re-enters the US under an assumed name; the FBI seeks him, and so does Gibbs, with whom he served while on active duty. Gibbs finds him and figures it out.

With extreme determination Gibbs continues, to the extent of obsession, to concentrate on the unknown terrorist who shot him and escaped. The bad guy reappears, but Kate and Tony disappear temporarily. Gibbs eventually meets his quarry.

A civilian dies on a Marine bombing range; while investigating, Gibbs finds a second body; other bodies also later appear. The NCIS and the FBI strangely work well together, and the NCIS team work well together, so they produce results.

A petty officer reports that someone has assaulted her; the NCIS investigates. The victim has a mental illness and has had an affair with a captain under investigation by the FBI; she soon dies by murder. The team figures out everything.

Tony returns early, in time to rejoin the team in an investigation of a shooting of two Naval aviators. Tony finds a bomb, then it explodes; Gibbs says that someone has again tried to kill the NCIS gang, which loses one of their members.

Ducky meets Ari, Tony follows Ziva, Ari secretly betrays Israel and Mossad, Ziva passes cash and a fake passport to Ari, Gibbs and Jen seek Ari but miss him, Ari finds Gibbs, and Ziva finds them. The gang attend Kate's funeral in Indiana.

Tony and Ziva go undercover and under the covers as assassins, a married couple, who recently died, but who apparently have a contract to execute at the Marine Corps birthday ball in Washington. The NCIS gang figure it out and work it out.

The amputated legs of a young woman turn up aboard the Marine Corps Base, Quantico, Virginia; Gibbs and company investigate. Forensic evidence implicates Tony because a pro has framed him. Abby works hard, and the gang find the bad guy.

A former petty officer and federal prisoner, convicted of murder and bank robbery, escapes and contacts Fornell, who, with Gibbs, caught him. Fornell contacts Gibbs, who contacts Jen, who temporarily reinstates Gibbs. The team solve it.

While replacing a furnace at Quantico, workers find a smoked body in the chimney; Gibbs and company investigate. Fornell shows interest, saying that the victim was a serial killer. Abby enables Gibbs and Fornell to confront the real killer.

Jen meets with an informant about the Frog, but someone kills the witness; Gibbs and company investigate. Jen obsesses about catching the Frog. Abby produces many answers; although the gang persist, they find a surprise but no Frog.

Jen returns from Paris; at home she finds a curious sight. All NCIS agents in Washington must take polygraph tests; Gibbs and the gang look into that. Tony and Jeanne deal with an injured pedestrian; Jeanne introduces Tony to her father.

While demonstrating an autopsy, Ducky announces murder; Gibbs and company investigate. The victim worked for the FBI, which tried to catch a person who erased old identities and created new ones. The NCIS and the FBI catch the bad guys.

Fornell and his Hoovers arrive in the squad bay; he tells that the Gibbs team is under investigation for the murder of the Frog. However, the Gibbs gang investigates the FBI, and they put the pieces together and explain them to the suits.

A neighbor finds the body of a tortured Marine; Gibbs and company investigate, and they encounter Fornell, who says that a person of interest is also a key witness in a major murder case. Another Marine dies, and the gang connect the dots.

During a poker game at the home of the SecNav, an ICE agent dies while on the protection detail; Gibbs and company investigate with support from the FBI and ICE. An invisible man becomes visible and dead. Tony arrests Michael, who resists.

The death of a Marine veteran gets the attention of Gibbs, Fornell, and the gang. Damon reappears, then he and Ziva pose as truckers. McGee and others figure out everything, then Gibbs, Fornell, Damon, and Ziva round up the bad guys.

The body of a Navy petty officer, shot and drowned, washes up on a beach; while Gibbs and company investigate, another body, wrapped in chain, turns up. The FBI becomes involved, the gang find clues, and Fornell and Gibbs find a leak.

A woman Marine sergeant, who's a bomb-disposal tech, shoots to death an intruder in her pad; Gibbs and company investigate; Fornell and another FBI member become involved. The gang find everyone and figure out everything; it all works out.

In a national forest near Washington, DC, a young couple find the body of a Navy lieutenant commander in his dress-blue uniform; Gibbs and company investigate; on a rock nearby Tony finds a single word written in the victim's blood. The Metro PD finds the victim's abandoned car in Washington. Ducky finds that the shooter used ammunition of an unusual type, Gibbs and McGee talk with a specialty publisher, and Tony and Ziva find the body of an FBI agent, so Fornell enters the picture. The publisher leaves the country, then Gibbs and Fornell speak with the author of a mysterious book, who tells them about the contents. Tony, McGee, and Ziva arrive at a self-store room in time to see two stars and a couple of helpers get blown up; the admiral recovers well enough to go home, and he gives Gibbs and Fornell a lead; they pursue it, but Abby says to hold the phone, then she directs them to the real killer, and they nail him.

Diane, the mutual ex-wife of Gibbs and Fornell, gets help from them; Victor, her current husband, has disappeared; they and the gang find the pieces, put them together, find the bad guys, and deal with them. Diane gives Gibbs a watch.

At a diner an unknown person with a drawn pistol approaches Gibbs, who deals with him; then Gibbs experiences flashbacks and fantasies, which Franks explains. The next day McGee announces a decision, then the gang gear up and head out.

After the attack on NCIS, the President orders all agencies to pursue Harper Dearing with "extreme prejudice". Meanwhile, Ducky tries to recover from his heart attack.

A Navy seaman fires on Fornell, who returns fire and kills him; Gibbs and company investigate, along with Fornell and the mutual ex-wife of Gibbs and Fornell. The gang find frozen fish, a dead body, a missing accountant, and two bad guys.

A familiar face defends Gibbs in Parson's investigation. While the team tries to help Gibbs, they must solve the murder of a Navy SEAL.

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 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.

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 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.

Gibbs and the rest of the NCIS team, along with FBI agent Fornell are on the hunt for an American born terrorist who was detected in Syria but is now back in the D.C area.

Gibbs and the NCIS team continue to track down the Russian terrorist Sergei after two young Marines are killed in a bombing. Agent Fornell struggles to cope with the recent shooting death of his ex-wife at the hands of Sergei.

Gibbs fights for his life after being shot by Luke Harris. Meanwhile, Agent Tony DiNozzo and CIA officer Joanna Teague travel to Egypt to take down The Calling.

The Secretary of Defense turns to NCIS to help a sailor dying from leukemia locate a bone marrow transplant after two of his siblings are killed in the line of duty. Meanwhile, Bishop returns home to Oklahoma for Thanksgiving after learning of Jake's cheating.

The team partners with the FBI to rescue the kidnapped daughter of Sarah Porter.

A family owned mortuary ordered a bunch of caskets from an overseas company. When they go to unload the shipment, they find that one of the caskets already has a dead body. There are ties to a prison break of someone NCIS helped put away.

Gibbs and the team investigate a military home invasion thwarted by a 14-year-old, while Vance and Fornell head to London to continue pursuing the escaped British spy.

The team continues the international manhunt for an escaped British spy while a colleague fights for their life in the ICU.

The NCIS, FBI and MI6 teams continue the international manhunt for an escaped British spy who's targeting current and former agents. Anthony DiNozzo bids farewell to NCIS.

The team investigates a car explosion with a connection to an agent who went missing six months earlier; Gibbs asks NCIS Special Agent Alex Quinn to shadow his team.

A marine sergeant falls from a building, it appears she attempted suicide, but her psychiatrist, Dr Grace Confalone, urges Gibbs to investigate her attempted murder.

Ducky looks back on a choice he made 37 years ago when evidence in the murder of a Navy captain is linked to his dead mother.

Gibbs begins his own investigation when a convicted felon swears he was framed; FBI agent Fornell joins the team.

When the body of a missing Navy commander is found, Gibbs and his team are ordered to work with former FBI agent Tobias Fornell, the private investigator who was hired to find him.

NCIS makes a deal with Paul Triff to give him a 48-hour furlough at his former residence, now McGee's home, in exchange for information to convict Gabriel Hicks.

When evidence reveals an NCIS team member is a hitman's latest target, the team must search through old case files to determine who is seeking vengeance.

While Gibbs is on a quiet vacation in the woods, he is interrupted by his friends, Fornell and Brooks, and a case near his cabin.

Fornell pleads with Gibbs to do whatever is necessary to take down drug dealers in the area after his daughter is hospitalized from a drug overdose; Gibbs is haunted by aspects of the case.

Gibbs and Fornell attempt to track down the leader of a drug ring who supplied drugs to Fornell's daughter; the team deals with the case of a missing cadaver from the NCIS autopsy room.

The discovery of two dead bodies leads the team into the world of modern day treasure hunting as Gibbs and Fornell get deeper into their search for the drug kingpin.

McGee and his wife Delilah's Bahamian vacation turns into a high-stakes mission when a case NCIS is tracking of a dead escape room manager has ties to the island. Also, Gibbs fears the worst when his search for Fornell leads to blood.

Gibbs and Fornell's crusade to find the head of the drug ring responsible for Fornell's daughter Emily's overdose comes to a climax. Also, Gibbs and Vance finally let the team in on a case that has dangerous implications.

NCIS dives into the competitive world of food trucks after finding a man frozen to death in the back of one.

While trying to find the serial killer Gibbs was after, the NCIS team discovers another person has been tracking the case as well.

NCIS investigates the apparent suicide of a retired Navy officer who was in Palmer and Knight's grief group. Torres gets a call from Tennant to come to Hawaii when she gets a lead on a witness from a case they worked on together.

Alden Parker is still on the run with his ex-wife Vivian, now the team is investigating on who might have a personal vendetta against him in hopes of clearing Parker's name.