Tennant and NCIS must take down a notorious team of international thieves using WWII explosives on armored trucks before they complete their final big job and disappear. Also, Kai searches for a new place to live; Lucy and Whistler have a standoff about their previous encounter; and Ernie’s mission in the field is more alarming than he expected.
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Pilot
An experimental Naval aircraft crashes on Oahu, and Tennant and her team must find who is behind it before classified state secrets are exposed.
Tennant and NCIS must take down a notorious team of international thieves using WWII explosives on armored trucks before they complete their final big job and disappear. Also, Kai searches for a new place to live; Lucy and Whistler have a standoff about their previous encounter; and Ernie's mission in the field is more alarming than he expected.
When a Japanese sailor is killed on American soil and evidence links the case to the previous murder of the victim’s girlfriend back in Japan, NCIS must find the murderer before the wrong person is accused and the case triggers a diplomatic crisis.
When Tennant and NCIS are tasked with finding a kidnapped globe-trotting social media star, they find that she is not who her husband, or her followers, think she is. Also, the team is at odds with Whistler, who has an agenda of her own.
The NCIS team investigates a cold case involving WWII-era bones on the 80th anniversary of the Pearl Harbor bombings, and are shocked to learn they belong to a 100-year-old survivor of the attack.
NCIS crosses paths with Whistler's team while investigating a shipping container filled with contraband weapons; Tennant debates arresting Alex's friend's dad, knowing it will cause her friend to move away.
While Jane is questioned following Maggie Shaw’s arrest, the rest of the team investigates a mysterious case of Marines with damaged ear canals from a weapon that emits ultrasonic waves. Also, Ernie visits his friend, Dr. Tony Lee (Alec Mapa), to identify possible suspects who had access to his classified weapon.
As Jesse enjoys a day sailing with his daughter, pirates suddenly seize their yacht, take all the passengers hostage and attack Jesse, leaving it up to his team to quickly locate and rescue his daughter.
Kai goes undercover as a chef in a local restaurant to gather intel on a notorious criminal kingpin who has a connection to the eatery. Also, Jane discovers that a school on the mainland has recruited Alex on a baseball scholarship, which he's kept secret from his family.
When a ransomware attempt causes a dam to malfunction, Ernie and a team of hackers are tasked to find the culprit quickly, before all power and water is cut off on the island. Also, Lucy and Whistler work together, giving Whistler a chance to apologize to Lucy and mend their relationship.
NCIS Agents Nick Torres and Jessica Knight travel to Hawai'i when they learn a key witness in one of their old cases has turned up there with crucial evidence.
The crossover starts on NCIS S19E17 Starting Over (I).
Captain Milius returns to Hawai'i for a secret prisoner exchange operation and brings in Jane to be his personal security escort in the Philippines, where the exchange will take place.
Captain Milius continues to work with Tennant and her team in the aftermath of the prisoner exchange between U.S. and eastern Europe. Also, Whistler takes Ernie's advice and makes a grand gesture in the hope of winning back Lucy.
Tennant’s team, along with NCIS agents Nick Torres and Jessica Knight, track The Raven’s whereabouts to the island of Oahu and learn about his plans to attack RIMPAC (The Rim of the Pacific Exercises), the world’s largest international maritime warfare exercise.
The crossover starts on NCIS S20E01 A Family Matter (I).
Tennant and the NCIS team suspect foul play when they investigate a fatal car crash involving a Navy officer who turns out to be an imposter. Also, Whistler finds herself in danger when she goes undercover to learn the truth behind the accident.
When a Navy sailor washes up dead in a sacred, forbidden kapu site, the NCIS team brings CGIS Special Agent Pike to unmask the mystery and catch a possible serial killer on the island. Also, Tennant meets Alex’s new girlfriend.
The NCIS team investigates the death of a Navy sailor and goes head-to-head with a ruthless local criminal organization. Also, Lucy looks for a new apartment.
When a Marine corporal dies in a tide pool after being exposed to fentanyl, the NCIS team must quickly find the source of the drugs; Alex talks to his parents about taking a gap year; Ernie reveals personal news to Lucy.
When a naval officer is murdered while moonlighting in community theater, the NCIS team recruits a familiar face to help lead them to a ruthless international killer. Also, Kai enlists Whistler to open an investigation into an old friend turned criminal.
Tennant, Jimmy Palmer and Sam Hanna find themselves captured with a woman who claims to be a CIA agent demanding intel from the team. Also, Jesse, Ernie, Whistler and Alden Parker learn about an asset that arrived in Hawai’i who could be connected to several overseas assassinations.
The crossover starts on NCIS S20E10 Too Many Cooks (I). It continues on NCIS: Los Angeles S14E10 A Long Time Coming (III).
Following a close call at a meth lab explosion, the NCIS team learns Kai is being targeted by his old friend-turned-criminal and must take him down; Lucy gets her first big case aboard her aircraft carrier.
When the murder of a captain and his wife echoes a previous case, the NCIS team brings in a former team member to help determine if they are dealing with a copycat killer.
When a Navy deserter accidentally comes out of hiding, his family becomes a target that drives the NCIS team and Charlie 1 to investigate who is after them. Meanwhile, Lucy surprises the team by returning to Hawai'i from her agent afloat job early.
When Navy residents discover their vehicles were burglarized overnight, the NCIS team connects it to a series of peculiar crimes and tracks down an unlikely bandit. Also, Whistler struggles with an uncooperative CI and Alex weighs his college options.
The discovery of a dead former MI6 agent uncovers secrets from Tennant’s past, forcing her to go to extreme lengths to track down the responsible party.
When a figure from Tennant’s CIA past re-emerges, the NCIS team seeks help from the most unlikely place to catch a killer who threatens to destroy everything Tennant has built.
Following the crash of a prisoner transport plane, the NCIS team must find the convicts that escaped onto the island. Meanwhile, Sam Hanna and Tennant are tasked with locating a high-profile Russian prisoner known as "The Chemist".
After a brazen daytime robbery of a Navy Federal Credit Union, the NCIS team tracks down a group of adrenaline-seeking thieves. Meanwhile, Tennant grows suspicious of Sam Hanna's reasons for being in Hawai'i.
After a Marine's wife is kidnapped for ransom, the NCIS team uncovers dark secrets as they race to track down her abductor before it's too late. Meanwhile, Sam seeks Ernie's expertise decrypting a computer program that may have deadly ramifications.