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.

NCIS is called in when Navy Chief Warrant Officer Rafi Nazar is suspected of trying to sell stolen classified Navy software used to pilot combat drones.

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.

Following the cliffhanger season 19 finale, with Special Agent Alden Parker still on the run with his ex-wife Vivian, the team investigates who from his past might have a personal vendetta against him in hopes of clearing Parker’s name. Enlisting the help of NCIS: Hawai’i’s Special Agent Jane Tennant and computer specialist Ernie Malick, who are in town meeting with director Leon Vance in preparation for a global military exercise, the group tracks down their prime suspect, The Raven.

The crossover continues on NCIS: Hawai'i S02E01 Prisoners' Dilemma (II).

McGee’s personal life and professional life intersect when a dad from his children’s school is linked to a break-in at a government storage bunker.

When a dead body is found at an ancient burial site that is thought to be cursed, the team tries to determine the motive and the symbolism behind the crime. Also, as Torres continues therapy with Dr. Grace, he discovers that their lives are in danger.

Agent Knight's past resurfaces when her ex-boyfriend, a National Parks Service agent, teams up with NCIS to investigate a campsite murder.

Agent Parker steps up to protect Director Vance after a terrifying home invasion. Also, the team detects advancements in Jessica and Jimmy’s blossoming romance.

When an NCIS agent turns up dead and Kasie goes unaccounted for, the team must work quickly to find the killer.

NCIS must investigate the Secretary of the Navy when her husband claims she tried to murder him.

After an unknown shooter causes chaos at an annual Thanksgiving 5K, time is of the essence for the NCIS team to find the culprit. Also, Kasie joins Knight for Thanksgiving lunch at Knight’s sister’s house.

NCIS investigates the death of a college student who was killed while running across the street and had connections to McGee’s wife, Delilah.

NCIS agents from Washington, D.C., Los Angeles and Hawai’i, all in D.C. to attend the retirement party of a beloved Federal Law Enforcement Training Center (FLETC) professor, find themselves jointly investigating his shocking suicide.

The crossover continues on NCIS: Hawai'i S02E10 Deep Fake (II) and NCIS: Los Angeles S14E10 A Long Time Coming (III).

Parker discovers he's a victim of identity theft while investigating the unusual murder of a Navy ensign; Knight and Jimmy face hurdles in their relationship as their connection heightens.

When an old pal of Torres’ comes to him, disheveled and bloodied for guidance amidst an undercover FBI operation and then disappears, NCIS helps track him down. Also, McGee prepares to be a contestant on a popular game show

In preparation for a role, a world-renowned actress shadows the NCIS team as they investigate a decapitation case.

Parker grapples with his emotions when a conman from his past turns up as a prime suspect in the murder of a navy officer transporting millions of dollars’ worth of opioids.

NCIS investigates the death of a ride-share driver who was found after a car accident. Also, Parker’s dad, who is temporarily living with him, assists the team in their investigation.

The NCIS team jumps into motion to investigate who is responsible for a potential bioterror attack at a strip mall parking garage; Knight's father deals with a health scare while in Japan.

NCIS works to solve the murder of a Marine private who appears to have been killed for helping an Afghan refugee. Also, Jimmy navigates the pressure of parenting his teenage daughter, who is eager to go out on an unchaperoned group date.

The NCIS team digs deep to investigate a Navy lieutenant who’s accused of trying to murder her husband but has no memory of the attack. Also, Kasie navigates a potential medical scare.

Agent Knight goes viral for saving a mother and child from a potentially fatal car accident.

NCIS works to solve the murder of a senator’s daughter who has a rebellious reputation and large online following. Also, Jimmy gets competitive with an old college rival.

When a suspicious murder occurs in the classified section of the National Archive, NCIS must investigate a string of Russian spy encounters that may be linked to the crime. Also, Jimmy accidentally makes a confession that could change the course of his relationship with Knight.

Agent Torres finds himself in prison as the team tries to stop an impending terror attack on U.S. soil.

The NCIS team must help Torres when he puts his future at stake by confronting the man who tormented his family when he was a child.

As NCIS mourns the loss of Ducky, the agents find comfort in working on one of his unfinished cases involving a woman whose father was dishonorably discharged from the Marines.

When the NCIS team engages in Walk-a-Mile day to gain a new perspectives on different departments, things take a turn when Kasie receives a distress call from a mysterious man.

The NCIS team is in a race against time to find a missing officer who disappeared during his wedding proposal.

With the help of Knight's dad, NCIS works to unravel the mystery of a recently used service weapon belonging to a missing agent. Also, McGee is in a tailspin when DNA results reveal a close relative he was unaware of.

After discovering a navy pilot's body riddled with unusual wounds, NCIS' investigation draws the team into the rabbit hole of UFO conspiracy theories.

NCIS comes under attack by a mysterious enemy from the past. Also, Vance tries to mend fences with his estranged son by explaining why, despite the ongoing dangers of his job, he still chooses to stay at NCIS.

The NCIS team looks for a motive behind the kidnapping and death of a famous heart surgeon.

After discovering the remains of a Marine captain, the NCIS team travels to Texas to interrogate the suspected killer.

Parker and Knight discover three bodies on an old Navy ship that's about to be sunk and turned into an artificial reef, when they're suddenly locked inside by a mysterious figure. Also, Vance offers Knight a unique opportunity.