Season 15 begins with the NCIS team tirelessly searching for Gibbs and McGee two months after they were last seen fighting an elusive group of rebels in a Paraguay jungle. Meanwhile, Vance and Torres are summoned to a congressional hearing regarding the fallout from the Paraguay mission.

NCIS investigates when the body of a murdered Navy lieutenant, who disappeared over a year ago, is found by a cemetery grounds crew while relocating caskets on the property. Meanwhile, Gibbs and McGee must pass a psych evaluation before they can officially resume working.

Torres' partner mysteriously vanishes during a stakeout with Metro P.D. The investigation uncovers new evidence from a decade-old murder case. Meanwhile, Ducky's friend, Cadence Darwin, presents him with a new opportunity during his guest lecture series.

NCIS Special Agent Jacqueline Sloane, a forensic psychologist, joins the team just as a horrific storm shuts down Washington, D.C. During the power outage, a sailor is kidnapped, and Torres and Bishop go out to sea to track evidence.

Reeves sees his friend get kidnapped and the investigation reveals the primary suspect disappeared two days earlier with confidential military information. Meanwhile, an embarrassing photo from McGee’s teen years becomes a popular meme.

A petty officer is found murdered on a golf course, and McGee spends hours on the victim’s ham radio trying to locate a key witness. Meanwhile, Palmer asks his co-workers to donate to a charity that builds playgrounds for kids of all abilities, and Torres surprises them with his generosity.

A convicted felon claims NCIS framed him for murder a decade ago, so Gibbs investigates and asks Ducky to conduct a new autopsy. Meanwhile, Senior FBI agent Fornell joins the probe, since he was the lead investigator in the original joint FBI and NCIS case.

An NCIS person of interest in a bribery and fraud case is found murdered after a runner is led to his body by a strange voice. Also, McGee and Delilah disagree on whether to find out the baby’s sex or keep it a surprise.

The team tracks an elusive international arms dealer who recently murdered an MI6 officer; Abby races Delilah to the hospital when her labor starts three weeks early.

As Torres and Sloane run protection detail for U.S. Senator John Phillips in Afghanistan for the holidays, they must urgently return to the states after hearing the senator’s son is in the ICU. Also, Gibbs and the team investigate the altercation that caused the life threatening injuries to the senator’s son.

Torres and Bishop go undercover as a criminal couple available for hire, during an NCIS sting operation tracking illegal drug-running out of the Norfolk civilian marina.

After a seemingly happy and successful Navy lieutenant appears to have taken her own life, Gibbs and the team conduct a thorough investigation, interviewing family and friends from her past and present.

After McGee and Torres visit the home of a high schooler who witnessed a hit-and-run, her parents, Christopher and Julie Bell, flee with their daughter, leaving NCIS in the lurch. Also, Vance’s daughter is arrested for shoplifting.

After the body of a missing Navy commander is found, Vance orders Gibbs and the team to work with former FBI Agent Tobias "T.C." Fornell, the private investigator who was hired to locate him. Also, Bishop and Torres interview convicted investment advisor Albert Hathaway when the victim is linked to his highly publicized trial.

NCIS strikes a deal with convicted murderer Paul Triff, giving him a 48-hour furlough at his former residence, now McGee's home, in exchange for information that can convict his former cellmate, Gabriel Hicks, the murderer who deceived Gibbs and Fornell.

Gibbs and the team work to clear the name of retired Marine Sergeant John Ross when cyanide is found in one of the hundreds of care packages he sends to active-duty Marines.

Gibbs and Ducky are watching TV when they see the host handling a 200-year-old war stick that could be a match from a decade-old cold case.

The NCIS headquarters are evacuated after the team discovers a body as well as bomb materials on the roof of the squad room. Also, the team reads the first draft of Ducky’s book.

Gibbs is granted protective custody of a 10-year-old orphaned refugee, Elena, when an NCIS case reveals she is the target of a violent gang.

NCIS searches for a petty officer suspected of assault who escapes when the sheriff transporting him crashes into a lake. Also, Torres works closely with Annie Barth, a key blind witness who heard vital evidence needed to solve the case.

Sara Carter begs Gibbs to investigate her mother's murder; she believes the wrong man was convicted; Abby is awarded a dinner reservation for two to a new five-star restaurant in an igloo and has to decide which co-worker deserves to go with her.

When evidence reveals an NCIS team member is a hitman’s latest target, the team must search through old case files to determine who is seeking vengeance.

While Gibbs attends the memorial service for a friend who was lost at sea, he discovers that the deceased, Navy Captain Phillip Brooks, has been hiding in a fallout shelter after his boat was attacked and he swam to shore.

Sloane is adamant that a man who held her hostage and tortured her years ago in Afghanistan, and was believed to have been killed following her rescue, is alive and in D.C. Also, Vance and Gibbs fear Sloane is willing to risk everything to destroy this man.

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.