When an ambulance explodes while carrying the remains of a Marine's body that was killed in a car crash, the NCIS team is called in to investigate what actually happened. The investigation leads them to some sudden discoveries -- the DNA of the victim found in the ambulance doesn't match the Marine's DNA; the ambulance was set up to explode; and the family of the dead Marine is hiding a very important secret.

While working on just a regular murder case with the rest of the NCIS team, Abby is almost killed by an evidence from the case and soon it becomes clear that the murder was staged, and that someone wants Abby dead. The team discovers some enemies from Abby's past, and they must find out who is the person, before the person kills Abby.

Gibbs is forced to come back out of his retirement to help Fornell, who is being threatened by a convict that escaped from prison. The convict threatens both Fornell and his daughter Emily. Gibbs and the NCIS team re-open the convict's old robbery case, and question a retired sailor who is the only one who contacted the convict after he was sent to prison. The investigation will lead the NCIS team to a surprising discovery.

McGee breaks the rules, risking his NCIS job, to help his sister Sara, who shows up disoriented and bloodied. While he works on figuring out what happened to his sister, the NCIS team is investigating a case of a Navy sailor, who is somehow connected to McGee's sister. Both Tony and Abby are busy with love problems, while McGee turns out to have another secret.

When the NCIS team learns that the missing 10 kilograms of highly toxic chemical weapons are now in the hands of Mamoun Sharif, a wanted terrorist, they will have to find a way to find the man and stop him before it's too late with the aid from Army Lt. Col. Hollis Mann and constant phone calls from Sharif himself.

Director Shepard makes a huge mistake by meeting a man alone to inform her about Le Grenouille, as their meeting turns into a murder of the informant. Now the NCIS team must gather all the existing info and try to finally hunt down their enemy.

When a blind photographer shoots the body of a Petty Officer on film, the NCIS team uses his special insight to investigate the crime. Meanwhile, both Gibbs and Tony are having commitment issues in their relationships.

During an autopsy, Ducky makes a startling discovery that turns a murder of a Petty Officer into a search for a missing infant. Meanwhile, Tony has to deal with his feelings for Jeanne.

When a former NCIS agent is found dead, the entire team is put in danger as they hunt after the killer.

When one of their own is killed, the team must find the killer before they get to another member of the team, Gibbs. In an emotional investigation, the team tries to stay together, against the wishes of Assistant Director Vance.

Gibbs and his team are searching for a cyber serial killer who takes videos of his victims. The team quickly finds out that the video's of the dead victims are false.

The team discovers a link between a sergeant's murder and his possibly treasonous private life.

A murder prompts the reopening of one of Tony's old investigations, leading Gibbs and DiNozzo to reverse roles to solve the case.

When a government scientist goes missing, Abby is recruited to carry on his work, but the team worries that she may meet the same fate as her predecessor.

The team discovers the bizarre death of a Marine and his two friends may be linked to their past, but its Gibbs who ends up taking a trip down memory lane.

The team literally finds themselves in the dark when the investigation into the death of a lieutenant is connected to a city-wide blackout.

The team finds themselves in a race against time when a terrorist group threatens to detonate a "dirty bomb" in the D.C. area.

When an NCIS polygraph specialist's night job takes a dangerous turn, Gibbs, Fornell and the team have to uncover the truth.

The team tries to track down a serial killer, while Abby heads south of the border to give a speech with McGee in tow.

The NCIS team has to find a young girl that was kidnapped, but their investigation turns into something else when her grandfather gets way too involved.

The NCIS team investigates the disappearance of a Navy petty officer who is the sole witness in an upcoming murder trial.

The dismembered fingertips and teeth of a murdered Marine are discovered in the stolen purse of a pickpocketer, launching NCIS on a mission to find a cold-blooded killer.

After Tony's ex-partner, Danny Price, appears to be the Port-to-Port Killer's latest victim, he revisits his days as a detective in Baltimore, including his first encounter with Gibbs.

The NCIS team uncovers a startling surprise after a young Marine shows up to his homecoming party with a fatal stab wound.

The NCIS team searches for answers when the current husband of both Gibbs's and Fornell's ex-wife is suspiciously kidnapped.

When a Navy captain is found dead with an unusual costume hidden under his uniform, NCIS uncovers a secret society of real-life super heroes and must track down the villain.

The NCIS team analyzes what secrets could be in the hands of a terrorist targeting the Navy when a high-tech bug is found inside a probationary agent’s tooth. Meanwhile, the festivities for Jimmy Palmer’s upcoming wedding continue with the bachelor party.

While on medical leave, Ducky orders the exhumation of a Navy commander’s body from a case closed 12 years ago. As a result, Gibbs tasks Ducky with a slightly different role on the investigation. Meanwhile, the NCIS team investigates the recent death of a Marine. As both cases unfold, the team begins to question whether the two are somehow connected.

Gibbs teams up with FBI Agent Fornell on a joint NCIS/FBI investigation after Fornell becomes the target of a shooting, but they face an unexpected twist in the case when their mutual ex-wife, Diane Sterling, gets involved. Meanwhile, rumors run wild among the group after Diane stays overnight at McGee’s.

The NCIS team races to track down Ducky and Jimmy after the two disappear while transporting a body from a crime scene.

Gibbs and McGee travel to Afghanistan when a murder case leads them to an Afghan women’s shelter Mike Frank’s secretly supported for years.

Complications arise when the NCIS team discovers a link between a murder victim and the current boyfriend of Gibbs and Agent Fornell’s ex-wife. Meanwhile, NSA Analyst Ellie Bishop adjusts to joining the NCIS team.

After a bomb detonates in the dressing room at a military charity concert, the NCIS team must determine if the target was a washed-up ‘80s rocker or if the bomb was part of a larger scheme. Meanwhile, Jimmy prepares for fatherhood

Director Vance gives DiNozzo a special assignment to bring home an Admiral’s daughter from Paris, but he must turn to his NCIS team for help after he enters a controversial crime scene.

When a Navy Lieutenant is killed on his way to a private meeting with the President, the NCIS team must determine if the murder was part of a recent stream of muggings in the area or a targeted hit to keep intel secret.

Flashbacks into his past help tell the tale for Dr. Mallard as he and Bishop travel to England in search of answers to find out why an Englishman murdered in the United States would have a list of deceased Navy men on his person.

The NCIS team investigates copy-cat crime scenes while Gibbs navigates two ex-wives relentlessly trying to get his attention.

While visiting a pharmaceutical lab on a murder case, Abby is trapped with no communication to the outside world after armed men take over the building and hold everyone hostage.

After Ducky is attacked by a man claiming to have information about his half-brother who died decades ago, the NCIS team searches for the perpetrator, as Ducky recalls the final emotional days he had with his sibling. Also, with the holidays approaching, Bishop and Jake discuss the future of their relationship.

After the NCIS team tracks evidence from the murder of a Navy captain to Ducky’s deceased mother, Ducky looks back and questions a pivotal life choice he made 37 years ago. Also, the team exchanges holiday gifts, and Gibbs spends Christmas dinner with Fornell.

Bishop is more determined than ever to seek revenge for the murder of Qasim, her late boyfriend, after Gibbs and the team find a new lead in the Chen case. Also, Torres teaches the agents the art of pickpocketing.

When a Navy SEAL vanishes during an unsanctioned trip, Gibbs, McGee and Torres travel to an unpopulated area in Paraguay that's teeming with violent rebels.

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.

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.

One month after Director Vance was kidnapped, Gibbs is assigned the role of acting director in his absence while the team searches worldwide for his whereabouts.

McGee reluctantly visits his high school after the unique computer password he used as a teenager is linked to the murder of a department of defense contractor. The case escalates when an intruder breaks into McGee’s home in an attempt to steal his archaic high school computer.

Former FBI Agent Tobias Fornell pleads with Gibbs to do whatever is necessary to take down drug dealers and suppliers in the area after his daughter, Emily Fornell, is hospitalized from an opiate overdose. Gibbs is haunted by the personal aspects of the case and his history with vigilante justice.

With their lives in danger, Gibbs and Ziva’s rogue investigation takes an unexpected turn when a possible terrorist plot is revealed.

After Torres and Bishop are victims of a hit-and-run, Torres fights for his life in the Intensive Care Unit.

The team searches for answers when the body of a well-regarded Navy technician in the Reserves is found floating in a lake where a popular community event is being held. Sloane is caught off-guard when her daughter makes an unexpected request.

Flashbacks reveal the murder case that first introduced young Gibbs to NCIS and his introduction to young, new-to-America Ducky.

NCIS tracks a stolen laptop to the uncle of a young boy, Phineas, Gibbs’ former neighbor.

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