A case involving the murder of a drug dealer turns personal for Special Agent Sam Hanna when he discovers his former Navy Seal comrades are involved.

As the courtyard is being transformed with holiday decorations, the NCIS team races to solve the murder of a Marine by an exploding cell phone and to find the remaining men of his former EOD (explosive ordnance disposal) unit before another deadly explosion kills someone else.

The death of a Petty Officer leads the NCIS team to a teenager in Sam's life. Meanwhile, Hetty is concerned about the effect that the workload is having on the team.

The NCIS team races to save one of their own when they receive video evidence of Special Agent Dominic Vail being held hostage months after he was kidnapped.

The NCIS team jumps into action when video surveillance footage shows an ambush on a humvee transporting Marines in the desert. Meanwhile, Nate returns from his mystery assignment.

When a murdered antiques dealer's book of top-secret information goes missing, Hetty sends the NCIS team on a mission to find it.

After Callen catches a man breaking into his house, a former KGB operative leads the NCIS team to a shipment of counterfeit computer chips entering the United States.

A Navy SEAL imposter's death gives the team a lead on a missing canister used to make deadly bombs.

The NCIS team joins forces with the NSA to find the creator and controller of a software program linked to a cyber attack against the Department of Defense. Meanwhile, Callen continues searching for more information about his past.

The NCIS team must determine whether a dishonorably discharged Marine is the target of an international set-up or if he committed murder

The joint NCIS: Los Angeles and Hawaii Five-0 task force travel from Hawaii to Los Angeles, when the lead suspect in the case moves to the mainland with a deadly virus in tow.

The crossover starts on Hawaii Five-0 S02E21 Pa Make Loa (Touch of Death) (I).

A drone strike on a bomb-making compound in Afghanistan reveals the body of a recently retired Marine, leaving the NCIS: LA team to investigate why the Marine returned to Afghanistan and whether or not he betrayed the country he fought for.

The NCIS: LA team find out that one of their own has been compromised as they investigate the murder of a Navy contractor involved in illegal transactions of confidential data.

The team learns that someone from their past is targeting one of their own. Nate Getz attempts to help Nell get through a traumatic experience.

After NCIS fails to locate a mole in the department, Under Secretary of Defense Corbin Duggan insists on new leadership and takes over the Los Angeles unit from Hetty and Granger.

The team travels to Syria to apprehend a High Value Target where one team member is severely injured when the mission goes awry.

Hetty goes rogue, leaving the NCIS team completely in the dark, and the mole kidnaps one of the agents.

Following the kidnapping of Sam's wife, Michelle Hanna, Sam goes rogue from the NCIS team and attempts to stop his arch nemesis Tahir Khaled from ever targeting his family again.

Season 9 begins with Hetty turning in retirement papers and disappearing. A new executive director arrives and immediately makes staffing changes. Meanwhile, Sam, still mourning his wife’s death, insists that Callen find a new partner.

The team must find assailants who illegally crossed the border and attacked California Highway Patrol officers; Homeland Security sends Nell's older and bossy sister to assist with the case.

While Hetty is being tortured by her captors in Vietnam, Eric and Nell find a clue to her whereabouts, prompting the team to organize a rescue mission with very little information.

Callen, Sam, Kensi and Deeks join Hetty’s team from the Vietnam War, Sterling Bridges, A.J. Chegwidden and Charles Langston, in a dangerous and off-the-books rescue mission to save Hetty from her captors in Vietnam. Also, Mosley calls in Nell’s sister, homeland security specialist Sydney Jones, to assist the team in Los Angeles with processing evidence connected to Hetty’s time in Vietnam.

The NCIS team is in danger after their pictures, as well as Mosley and her son’s names, are included on a cartel hit list. Also, NCIS Deputy Director Louis Ochoa arrives with Special Prosecutor John Rogers to interview Mosley about the off-the-books mission in Mexico.

The NCIS team attempts to locate Mosley after she murders a cartel hitman and goes off the grid.

After months of planning, the NCIS family celebrates the wedding of Kensi and Deeks. Also, an old acquaintance, Anatoli Kirkin, pays Deeks a surprise visit on his wedding day and he isn’t alone.

After a Navy Seal is attacked while moonlighting at a security job for a successful marijuana dispensary, Sam personally vows to apprehend the suspect out of respect for the Navy Seal brotherhood

Callen and Sam travel to the USS Allegiance in the Persian Gulf to work with Navy Captain Harmon "Harm" Rabb, Jr. (David James Elliott) when the NCIS team uncovers ISIS sympathizers who are targeting military locations.

Callen and Sam run protection detail for retired Navy Admiral Kilbride in an operation to locate a missing Naval intelligence officer.

When Fatima is captured while on a mission and held for ransom, Callen and Sam enlist a deep undercover CIA agent, Kadri, to help get her back.

While Sam investigates the murder of an Iranian exile working to overthrow the current regime, he must also try to save Agent Rountree, a new agent who’s having an unexpectedly adventurous first day on the job, when he accidentally triggers a bomb. Also, Nell makes a decision about her future with NCIS.

When a Russian bomber goes missing while flying over U.S. soil, Callen and Sam must track it down in the desert and secure its weapons and intel before the Russians on board destroy the plane. Meanwhile, Hetty gives Nell a cryptic assignment.

When Nell sends Sam to meet an informant who plans to blow the whistle on a military secret, Hanna's life is in danger when the man tries to run him down and kill him. Also, Kensi and Deeks debate whether or not to buy their first house.

When NCIS investigates the murder of a man about to reveal the source of a massive counterfeiting operation, an old acquaintance becomes their prime suspect and reveals the true reason for her return. Also, Deeks struggles during training to become an official NCIS agent

When Callen goes to the National Counterterrorism Center on the pretext of interrogating a Russian asset from the crashed plane case he investigated months earlier, the tables are turned and he is detained, accused of being a Russian agent.

Callen and the team discover that Anna is being held by a group with ties to Anna's upbring and must rescue her before she is forcibly returned to Russia. Also, Admiral Kilbride makes Nell a serious offer.

Deeks is kidnapped by an associate of Kirkin’s in need of his help and NCIS investigates the shooting of a militarized dolphin equipped with a Russian microchip. Also, Beale makes Nell an interesting offer and Hetty returns.

While Callen suspects Hetty of keeping secrets about his past and Joelle surfaces in her quest to capture Katya, NCIS must track down an informant whose life is in danger. Also, Kensi and Deeks work to expand their family.

When a newborn child is found abandoned on a Navy ship, Kensi and Deeks search for the mother on board before she dies of complications. Also, Nate meets with Admiral Kilbride and learns about the CIA project from the ‘70s and ‘80s involving children.

NCIS investigates the kidnapping of Master Sergeant Boomer, a military working dog. Also, Sam looks to sell his boat so he can take care of his father who is suffering from Alzheimer's.

NCIS investigates after two men are blown up by their own explosives while attempting to break into a military base. Also, Callen wants to take the next step with Anna, and Sam moves in with his father, Raymond.

While Agent Rountree and Fatima are searching for Kilbride, who has been MIA, they are ambushed and learn that every member of the team has a $200,000 bounty on their head via the dark web. The NCIS team must save Agent Rountree and find Kilbride while every cartel, hit man, gang and psychopath hunts them down.

The crossover starts on NCIS S20E10 Too Many Cooks (I) and NCIS: Hawai'i S02E10 Deep Fake (II).

When an ATF agent goes missing, the agency seeks help from the NCIS team to investigate stolen military-grade weapons and locate the agent. Also, Callen and Anna continue to plan their wedding, Rountree’s sister interviews for medical school, and Sam encourages his father to take part in the drug trial.

The NCIS team continues the case with ATF and the stolen weapons. Also, Callen and Anna decide on an impromptu wedding.