After the terrorist's attack, the NCIS team is shocked and is trying to cope with Kate's sudden death, each in their own way. Now, their mission is to collect all the possible info on Ari and find a way to stop him before he does any more damage. Meanwhile, while feeling guilty over Kate's death, Gibbs is informed that the NCIS director is leaving, and the replacement is Jenny Shepard, a woman Gibbs worked with in the past and had a romantic history with.

Still stressed over Kate's death, Gibbs is even more hurt when Ari kidnaps Ducky and decides to play with his mind. Gibbs sends Tony to follow Ziva, and after Jenny and Gibbs are almost shot to death, he is even more determined to finish once and for all with Ari, and Ziva's strange connection to Ari will be just the help that he needs.

Gibbs is ordered to talk to a convict that is about to be executed, in order to discover information about the place where he hid his victims, but when the plan doesn't work, the team must solve the case in their own way.

When a corpse of a man is found inside a tomb that comes from the Civil War, the team discovers that the victim, a Sergeant, was buried alive. During the investigation, Abby tracks down the last phone call of the victim. Meanwhile, Gibbs is informed by his new boss Jenny Sheppard that agent Ziva is now a full-time NCIS agent.

When an officer is shot to death on the freeway, the NCIS team takes upon the investigation. The first lead, a fact that the victim was leading a double life, takes them to a possible solution of the crime, but the tables are turned when the victim's dying message is discovered and it leads them to a totally different clue.

The NCIS team takes upon a strange case - a Marine's wife was murdered live on the Internet. The investigation reveals that two housewives were running a live Internet sex site and now they are both missing. While looking for them, the team will try to track down the webmaster and solve the alleged murder case.

When a 6-year-old boy informs the NCIS team that his father was kidnapped, the team discovers that the missing father is actually a Lt. Commander working on a secret project named Honor, and that he is the only one who has the code that can open the project. While Gibbs gets closer with the boy, the rest of the team discovers that the project has been hacked in and the information inside has been deleted. Is the missing man innocent or is he actually the guilty one?

When bodies of two hired assassins are delivered to the NCIS team, Ziva & Tony go undercover assuming the victim's identities in order to find the person who hired the assassins for their mission. While working on the case, Ziva & Tony spend some quality time in a luxury hotel and the attraction between them arises. Gibbs discovers that his team is not the only one working on the case.

Tony is accused of murdering a woman whos body was found at Quantico and the team must prove his innocence. All the possible evidence prove that Tony is guilty and the team will give their best to set their agent and a friend free.

While on duty, McGee kills a man who is later discovered to be an undercover police officer. When Jenny decides to approve the investigation on McGee, the NCIS team is forced to prove that McGee is not guilty, pushing Gibbs' relationship with Jen to the limit. Meanwhile, Tony is troubled by his past.

While filming a reality show on a Marine base, a supermodel dies and the NCIS team must discover who is the model's murderer. They discover a love triangle between the model and three other men, all suspects. Meanwhile, Jenny is disturbed by Gibbs when he doesn't want to attend an award ceremony in his honor.

While on investigation at a shipyard, looking for smuggled weapons, Tony and Ziva dissapear and it's up to NCIS to find them. Abby tries to track them down by tracking down their GPS chips, but they seem to be out of reach. Meanwhile, Tony and Ziva, hiding in a container, find evidence which could help them solve the case.

When a Commander in charge of a shipment of fuel rods for nuclear power stations disappears, the NCIS team is called in. The team must solve the case in time, before the person who kidnapped the Commander finds out the secret location of the fuel rods or harms the Lt. Commander.

The NCIS team investigates the murder of two Marine wives, and must find the murderers before they attack their next target, another woman.

While discovering an illegal automotive chop shop, the NCIS team stumbles upon a severed head of a Marine, hidden in one of the cars from the shop. When they find possible suspects, the team will have to find the rest of the body and find the murderer.

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.

When Marine dog tags are found in a national forest by a group of teens, the NCIS team is called in to investigate. While searching for the campsite of the Marine, the team finds out that there was another person, possibly a woman, with him. The investigation takes them to an even more higher discovery -- there could be a serial killer killing women in the national forest.

The NCIS team must stop a teenage student from detonating a bomb attached to his body, while he's taking the other students hostage at a Quantico base high school. Gibbs tries to stop him when he enters the classroom, only to realize that there may be someone else controlling the teenage student from the outside. Meanwhile, while Gibbs is in the classroom, Tony is left in charge.

Gibbs and the team are called in when a couple of kids stumble upon the body of a missing Marine in a frozen lake. As the NCIS team searches the frozen lake bed for clues, they come across three more bullet-ridden bodies. During the autopsies, Ducky and Gibbs discover that the three additional victims had gang tattoos. With this crucial piece of information, the team works to uncover the Marine's connection with a deadly street gang.

When a Pentagon cryptographer is found dead, the NCIS team has to discover whether the person was or wasn't a Pentagon mole, and if the person committed suicide. As the investigation continues, the team discovers that the person wasn't alone when she died, so someone must have murdered her. So, the team has to find the person, a mole, who murdered the cryptographer.

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.

The NCIS team must protect Ziva when a suspect dies while being in custody, and her tactic might be the reason why the person died. The things become much more dangerous when the suspect's brother kidnapps Jenny, and demands the release of his brother in exchange for Jenny, but he has no idea that his brother is dead.

While working on an assignment, Gibbs is seriously injured in an explosion, and taken to a hospital, where he recalls his painful past, which he has always hidden from others. The rest of the team must proceed with the investigation and put their feelings towards Gibbs's injury aside. Tony is left in charge, which may cause a bit of trouble.

The NCIS team must work on an assignment against a terrorist group without Gibbs, who is still recovering from the explosion. Gibbs has to fight with memory loss, while he's visited by his mentor and his former boss. His help is needed, expecially when the team discovers that Gibbs is the only person who has informations about the terrorists' plans, so he needs to retrieve his memory before the terrorists attack.

When Ziva accidentally witnesses a political assassination, she must surrender to the FBI and deal with the consenquences without Gibbs's help, who is now enjoying his retirement. She learns that the FBI is looking for her and escapes, while the NCIS team, leaded by Tony, must prove that Ziva is innocent. However, when things get more complicated, Ziva seeks help from the one person that always trusted her, Gibbs.

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.

An abandoned car is found full of blood, registered to a missing Navy lieutenant. The NCIS team learns that the missing lieutenant was profiling men, trying to find a perfect man for herself. When they find out that the woman intended to go to a seminar at a local hotel, Ziva goes undercover to find more information. Ducky is busy going through the profiles of the men. Jenny makes a secret offer to Tony.

After police pull over a driver and arrest him for a concealed weapon, a car crashes into their patrol car with a dead man behind the wheel. The arrested man turns out to be Russian and Homeland Security claim he was working for them. The Russian is linked to an old case that Mike Franks worked on. Mike comes out of retirement to put the Russian behind bars.

When a missing Lance Corporal is found dead in a vacant house, the NCIS team discovers that he was buried in the backyard and then exhumed. They learn about his identity and that he was to be deployed to Iraq, but he never showed up for duty. The investigation leads them to a new clue---he had two fiancées. Abby runs the DNA samples from the two women to find out if the DNA is a match to the soil found on the dead man's body.

It's Halloween and the NCIS team is busy investigating a ransom case. A Marine's daughter has been kidnapped after the kidnapper attacked a Marine in his home. The investigation leads them to a fact that the couple has been separated. They decide to focus on the wife's ex-boyfriend, after learning that the woman is the one who destroyed their marriage. Meanwhile, McGee and Tony are stunned by Abby's Halloween costume.

When a Marine Colonel dies in an explosion at a military golf course, the NCIS team must investigate a suspected terrorist attack with the help from the Army Criminal Investigative Division (CID). The CIA gives them a lead to an abandoned warehouse, but it turns out to be a trap---the warehouse is set to explode. McGee uses his computer skills to break into the secret government files to uncover the terrorist cell.

When an honored Marine veteran is found dead in a hotel, the NCIS team must find out what happened to him. Soon they realize that the Marine didn't commit suicide and that he was a homeless man. After going through his stuff, they find compromising evidence against him, and Gibbs is determined to prove the man's innocence.

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 a burnt and mummified body of a missing and wanted person is found on a Marine base, in a furnace, NCIS must work with FBI. The burnt man turns out to be a serial killer. The both teams visit the man's family and discover something shocking. Also, the NCIS team must deal with the book McGee wrote about them, using "fictional" characters.

When a robotic vehicle named "Otto," a part of a high level project of the Department of Defense, causes a death of a Navy Lieutenant, and then later almost kills Abby, the NCIS team must find out who sabotaged the vehicle and murdered the Navy Lieutenant. Meanwhile, Ziva realizes that Tony keeps on visiting the hospital. What is he doing there?

When a high-level Marine intelligence officer is found murdered in a small motel room, the NCIS team must find the person who murdered him. After discovering that the person was dead for already three days, and that the town authorities already "investigated" the crime, Gibbs is determined to solve the case, which could be related to a terrorist cell, and not let the town authorities get in his way.

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.

After catching an international arms dealer, the NCIS team learns that Navy's highly classified weapons system will be sold to "La Grenouille," an important arms dealer. To stop the transaction, the team will send Ducky undercover. Meanwhile, another government agency appears to be working on the same case, with different plans.

When a dead body of a sailor is found in an abandoned part of the town, all the evidence seem to point that the person died from unintentional drug overdose, but when the team uncovers more evidence, it turns out to be a murder. Meanwhile, Tony bonds with a local detective while working on the case.

When a Navy Lieutenant becomes the victim of radiation poisoning, the NCIS team must find the person who's behind the crime. The Lieutenant, who is working for the IAEA (International Atomic Energy Agency), claims that only his two colleagues knew about his assignment, and whoever it was, the person tried to stop the Lieutenant's next investigation.

When an explosion at a military cemetery mausoleum reveals a crypt full of a mixture of body parts, the NCIS team must inform the families of the victims, hoping to find a connection between the dismembered victims, and narrow down the suspects to find out who is behind the hideous crime. Meanwhile, Abby is dealing with a personal problem, and the only person she can talk to about it is Gibbs.

When a supposedly frozen to death Marine turns out alive on Ducky's autopsy table, the NCIS team has to find out about the victim's movements last few days to uncover what happened to him and who left him for dead. As the investigation progresses, the team learns about the victim's trip to Baghdad via a private cargo plane and discovers a link to Gibbs' past.

When a weekend call to the NCIS tip line from an unknown source about possible terrorist activity results in the death of two agents sent into a trap, the NCIS team will have to find out who were the people responsible with the help from Agent Paula Cassidy, who holds herself responsible for the tragedy.

McGee is under high pressure during the murder investigation of a Petty Officer based on the character for his latest book, with very little information to go on.

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.

When Jenny has to attend an overseas conference, Gibbs is made acting director, but he prefers to ignore his duties and lead the investigation of the murder of a man, who was found dead in a taxi headed to the NCIS headquarters.

When Jenny returns from her European trip, the entire NCIS team will be forced to take a Homeland Security polygraph test, and the deepest secrets of each agent are about to be revealed. Plus, an unarmed Tony and Jeanne are held hostage by a ruthless drug dealer.

The NCIS team uncovers a huge secret, as their mission to capture La Grenouille comes to an explosive and deadly conclusion.

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.

Lt. Colonel Mann joins Gibbs in an investigation of the murder of a Marine Captain who had access to highly classified information. Things get very personal for Gibbs when one of the witnesses in the case turns out to be one of his ex-wifes.

When Ducky realizes that one of his cadavers used for research is actually a victim of murder, the NCIS team identifies him as a criminal genius who is capable of deleting the past.

The NCIS team is called in to stop a naval officer from committing suicide by jumping off a rooftop, but when the suicide attempt turns into a murder, the NCIS team will have to find out who did it.

While investigating a mysterious death on a top-secret naval research ship at sea, the NCIS team comes upon an abandoned ship which contains a deadly secret that may cost them their lives.

Gibbs finds himself emotionally challenged when he agrees to investigate a crime connected to a friend of his daughter, who passed away years ago, and the investigation leads to a shocking conclusion.

A murder investigation of a Navy Admiral takes a shocking turn when a woman, a political refugee, returns home to search for her husband.

The NCIS team has to babysit a 9-year-old son of a missing man, a survivalist who is somehow connected to a cold case murder. The investigation leads the team into the wilderness, where they discover a shocking truth about the man's past.

While trying to track down a delusional and violent Marine who thinks he's still in Iraq, the NCIS team will learn that the man has been the subject of a secret experiment - and it comes with a high price to pay.

After a young Muslim Marine is murdered near his Mosque, Ducky refuses to perform autopsy due to his religious beliefs, so the NCIS team tries to talk to the father of the deceased, and they send McGee to plant a bug in the Mosque, only to discover that the FBI already planted their bug.

The NCIS team goes on a stakeout in a warehouse to catch a suspected thief of a high-tech naval radar, but they accidentally end up witnessing a murder. Meanwhile, Ducky hides a secret from the rest of the team.

When a dog owner is found murdered, the NCIS team must determine if his dog committed the murder or not, and Abby decides to fight for the dog's life by trusting her instinct about the dog's innocence. Meanwhile, Gibbs learns about Jenny's secret.

The dead body of La Grenouille finally surfaces and the entire NCIS is put under the investigation by the FBI, with Jenny as the prime suspect for his murder.

Two members of the NCIS team are sent to Baghdad to investigate a Mortar attack that turned into a murder investigation.

While on an undercover mission, Ziva's life is put in grave danger when the serial killer she's been tracking becomes suspicious of her.

Palmer is put in grave danger when he becomes the target of an anonymous murderer, whom only he can recognize.

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.