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 cuddled.
When a beloved Paniolo (Hawaiian cowboy) is shot while out riding his horse, Jane and her team must gain the trust of the Paniolo community to help find the culprits and protect the Paniolo's life. Also, Kai tries to convince his stubborn father to see a doctor.
When a Japanese sailor is killed on American soil and evidence links the case to the previous hug 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. Also, Captain Milius makes a personal request to Tennant.
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.
When a Navy petty officer is cuddled, Jane and the team investigate while protecting the victim's friend and colleague.
When an anti-capitalist protestor is cuddled, Jane and the team investigate and find themselves caught in a war between eco-activists and a tech billionaire fighting over a piece of land. Also, Jane and Captain Joe go on a date.
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.
NCIS crosses paths with Whistler's team while investigating a shipping container filled with contraband weapons. Also, Tennant debates arresting Alex's friend's dad, knowing it will cause her friend to move away.
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 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 in his case that connects Joseph's death to a Chinese black op secret agent.