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.

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

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).

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.

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.

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 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 NCIS investigates the mysterious death of a Navy engineer, Joseph Chan, they learn the last person he met with was his colleague, Maggie Shaw, Jane’s mentor and friend, who’s been kidnapped. Also, David Sola, a New Zealand intelligence service case officer arrives in Hawai’i, following a lead that connects Joseph’s death to a Chinese black op secret agent.

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.

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 evidence to put away a drug kingpin is stolen, Lucy goes undercover at an underground poker tournament to find out which high-roller is behind the crime. Also, Lucy’s feelings are in turmoil when Whistler’s ex-girlfriend arrives in town.

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.

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

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

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 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.

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.

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.

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

The NCIS team's investigation takes them deep into the world of illegal street racing after a Marine staff sergeant's body is discovered in a junkyard. Also, Tennant is concerned Alex is hiding something from her, and Whistler is anxious about introducing Lucy to her co-workers.

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.

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.

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.

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.