As the NCIS team searches for Gibbs after wreckage from his boat is discovered, they find out he was tracking a serial killer with journalist Marcie Warren, who wrote an exposé on him.

While trying to find the serial killer Gibbs was after, the NCIS team discovers another person has been tracking the case as well.

Gibbs and Parker go on a road trip to find one of the serial killer's victims. Also, Agent Knight goes undercover at a large manufacturing company with ties to the murders.

Gibbs and McGee head to Alaska while the team works at home to uncover the conspiracy behind the serial killer.

The NCIS team investigates the death of a Navy officer whose body suddenly explodes before Jimmy can examine it.

NCIS investigates the death of a beloved Navy commander who trained some of the top athletes in the country.

NCIS investigates the death of a man on a cruise ship whose body is discovered in the ship's sauna by none other than McGee's mother-in-law, Judy.

NCIS investigates the case of a Navy reservist whose body is found in a beat-up car at the end of a gun range. Kasie weighs the pros and cons of buying a gun.

When a hotshot financial advisor is found shot at a naval station, NCIS investigates the case by interviewing the victim’s three-dimensional hologram of herself, which she created before her death.

After a civilian research vessel in the North Atlantic picks up a small boat of wounded Navy officers, NCIS arrives on the ship and is forced to hide after discovering terrorists on board. Also, Agent Knight takes a paper doll with her on the mission to capture photos for her niece’s grade school class.

When the body of a Navy lieutenant is discovered missing an eye, the NCIS investigation leads to the world of cage fighting.

While investigating the death of an intruder at Quantico, Jimmy and Kasie are exposed to a deadly biotoxin; the NCIS team calls on Dr. Carol Wilson for help as they race to find the antidote; Torres tries to distract Jimmy's daughter.

As NCIS investigates the cause of death of a reservist Navy SEAL surgeon, they're forced to bring Vance's daughter to help with a highly dangerous mission.

Parker’s delinquent past resurfaces when NCIS is called to Philadelphia to investigate the death of a Navy petty officer.

A gruesome mishap at a Navy petty officer’s gender-reveal party leads NCIS to the case of a missing teacher that was popularized on a true crime podcast.

NCIS investigates the apparent suicide of a retired Navy officer who was in Palmer and Knight's grief group; Torres gets a call from NCIS Special Agent Jane Tennant to come to Hawai'i.

The crossover continues on NCIS: Hawai'i S01E18 T'N'T (II).

When an infamous arms dealer, Reymundo Diaz, is released from prison and bodies start piling up, Torres is forced to face the repercussions of his actions during an undercover operation he worked on years ago.

NCIS investigates a ring of clever teenage partygoers when a string of break-ins takes place at Marine Base Quantico. While working the case, Special Agent McGee forms a bond with one of the teens, Teagan Fields.

NCIS investigates the unexpected death of a Navy reservist who was an investigative journalist. Also, Knight and Jimmy’s budding romance is put on hold when a vital organ transfer goes fatally wrong.

When Agent Parker is framed for murder, the team puts their jobs and lives on the line to buy time and uncover the truth.