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. 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 marine is shot, the team investigates. They start by talking to him, he tells them that he went riding and he got shot probably by a hunter. They check out his story and learn he wasn't telling the truth. They go back to see him but he left the hospital, not fully healed. They learn a relative came and helped him. They see the relative, who doesn't know much but they find a bag filled with drugs. They think the bag belongs to his son. So they try to talk to him but he disappeared. They think the boy was asked by a drug ring to deliver the drugs but he changed his mind which means his father is trying to protect him. But the gang will stop at nothing to get them, so they try to find them. When Kai's father doesn't see his doctor, Kai needs to put aside his feelings to help his father.

A Japanese sailor is killed and evidence links the case to the 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.

The wife of a naval weapons Officer disappears. The team investigates and find the man who took her, dead. She left the vicinity around the time the man was killed. They look into her background but Whistler tells them to back off. Tennant relents and with the info they have, she deduces the wife works for the CIA. They find her but her husband gets taken. Whistler wants to take her but to save her husband, they need her.

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

NCIS team investigate the mysterious death of Navy engineer Joseph Chan, learning that the last person he met with was Maggie Shaw - Jane's mentor and friend, who has since been kidnapped. David Sola, a New Zealand intelligence officer who arrives in Hawai'i to follow a lead in a case that connects Joseph's death to a Chinese black op.

Mientras Tennant investiga el secuestro de Maggie, descubre la impactante verdad sobre el pasado de su amiga. Recibe ayuda de su equipo para demostrar que lo que descubrió es cierto.

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.

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.

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 and Ernie reveals personal news to Lucy.

En Washington D.C. para celebrar el retiro de un antiguo profesor. Los agentes del NCIS se ven obligados a investigar el suicidio del profesor. Tennant, Jimmy Palmer y Sam Hanna son secuestrados, y todo está relacionado con el misterioso suicidio.

Milius returns and asks Tennant to protect a girl who has info on a arms dealer the FBI and DOD want to arrest. Kai and Jesse are assigned and all she does is shop but it seems apparently That she has something else in mind. Kai tries to reason with her. Milius also reveals he was the one who got Alex into Annapolis. So he meets with her and Daniel which causes tension.