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.

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.

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).

When a Marine is murdered during training on the Big Island, the NCIS team tracks the suspect deep into the woods and discovers a disturbing secret.

While Jane investigates Maggie’s kidnapping, she’s shocked when she learns the truth and enlists her team and Whistler to prove her findings.

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.

Following a devastating ambush with a deadly bioweapon, the NCIS team must track down a mysterious terrorist group before they can strike again.

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.

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 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.

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.

Captain Milius returns to Hawai’i as the NCIS team works to catch a dangerous high-value U.S. Government target with the help of an informant unlike any they’ve ever encountered. Also, Tennant and Daniel deal with Alex’s acceptance into the Naval Academy

When Tennant interrogates a suspect during his helicopter transfer and the helicopter crashes, she must utilize her skills to save herself and the other passengers.

When Commander Chase is abducted from her home by an Army Ranger accused of murder, the NCIS team must act quickly to find her and the suspect.

When a high-value bioweapons expert is murdered in a secure facility on Hawai'i, NCIS and the NCIS Elite team join forces to track down the killer and discover an even deadlier threat.

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.

An experimental Naval aircraft crashes on Oahu, and Tennant and her team must find who is behind it before classified state secrets are exposed.

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.

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.

When a Navy petty officer is murdered, Jane and the team investigate while protecting the victim’s friend and colleague.

After the mysterious death of an astronaut in a highly sensitive Mars simulation, the NCIS team must send Ernie into the habitat to investigate alone.

When Special Agent Pike is ambushed while working undercover with a local Japanese crime family, the team must find the person responsible for orchestrating the attacks. Also, Kai goes deeper into his investigation regarding an old friend turned criminal.

NCIS is tasked to protect the daughter of a Russian oligarch carrying a deadly secret. Meanwhile, Sam asks Tennant for a favor.

When a Navy pilot is found murdered at a local military resort, the team goes undercover to discover a criminal enterprise hiding in plain sight.

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.

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".

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.

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.

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).

When the fiancée of a vanished naval officer seeks the help of NCIS, the team reveals his secrets go much deeper than she suspected. Meanwhile, Sam recruits Kai to be his wingman.

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.

After Tennant passes her medical and psych evaluations, she's surprised to see Sam's conducting her final interview to clear her return to work. Also, when the team discovers a breach in the U.S. Marshal's database, Sam joins Tennant in Las Vegas to locate the hacker.