Specialagent Tennants team, tillsammans med NCIS-agenterna Nick Torres och Jessica Knight, lär sig om planerna för en attack i Oahu på RIMPAC (Rim of the Pacific); världens största internationella sjökrigsövning.

Teamets undersökning leder till en värld av illegal streetracing efter att en marinsergeants kropp upptäckts på en skrotgård. Tennants oroliga Alex döljer något för henne och Whistler är orolig över att presentera Lucy för sina medarbetare.

Tennant och NCIS-teamet misstänker grovt spel när de utreder en dödlig bilolycka där en marinofficer är inblandad som visar sig vara en bedragare. Och Whistler befinner sig i fara när hon går undercover för att ta reda på sanningen bakom olyckan.

När en marinens sjöman spolas död på en helig, förbjuden kapu-plats, tar NCIS-teamet med sig CGIS Special Agent Pike för att avslöja mysteriet och fånga en möjlig seriemördare på ön. Dessutom träffar Tennant Alex nya flickvän.

NCIS-teamet utreder en sjömans död och går i strid med en hänsynslös lokal kriminell organisation. Och Lucy letar efter en ny lägenhet.

En marinkorpral dör i en tidvattenpool efter att ha blivit utsatt för fentanyl. Så teamet måste snabbt hitta källan till drogerna. Och Alex pratar med sina föräldrar om att ta ett mellanår och Ernie avslöjar personliga nyheter för Lucy.

När mamman till en ung pojke försvinner ger sig NCIS-teamet ut för att hitta honom och får reda på att de inte är de enda som letar efter honom.

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 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.

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 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.

When an elite special forces Marine captain is murdered, the NCIS team finds a suspect in a really unusual place.

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.

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.

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 Lucy receives a strange call on night watch from a man admitting to murder, the NCIS team sets out to find him.

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.