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.

Kai goes undercover with one of Hawai'i’s oldest surf gangs when a petty officer who’s trying to help wayward kids find a new path in the Marines is murdered.

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.

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.

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.

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.

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.

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.