Aboard a Turkish-flag ship an explosion occurs, killing one person and leaving Gibbs comatose with burns, abrasions, and a concussion; the team investigate. Eventually Ducky welcomes Gibbs back, but Gibbs does not remember him. [Continued.]

Gibbs regains consciousness, but he's lost his memory since 1991. He starts to remember a few things; Jen helps, then an old buddy, then Ziva. Gibbs gets back his memory and a solution, gives a severe warning, becomes ignored, then quits.

A bomb explodes as Ziva passes; a Syrian informant and two FBI agents die. The FBI seeks Ziva, who hides and calls Gibbs in Mexico. Gibbs and the NCIS gang band together to help.

A traffic stop, a car crash, a Russian man with a pistol and false ID, a dead Navy chief petty officer, and the bloody letters NCIS all combine to require the attention of Gibbs and company; Franks lends a hand. Together they wrap it up.

Someone attacks a Marine corporal and leaves him to die, facedown in a snowbank in a park; Gibbs and company investigate. Mike Franks shows up and takes part; he and Gibbs sort it out and work it out. Tony and Jeanne encounter a problem.

In Los Angeles, Jenny, with Tony and Ziva as a protective detail, attends the funeral for a retired long-time special agent, who supposedly died of a heart attack; Jenny hears a name, sees a man, makes pictures, and summons Mike Franks from Mexico; she tells him that she's the next person to die. Jen and Franks visit the home of the dead man; there they meet his girlfriend, whom they send to Nevada, but who winds up dead in Santa Monica. Jen and Franks check out an insurance policy at a diner in a desert, and she refuses help from Tony and Ziva; Franks steps outside in the back, then four men enter the diner, and gunshots ring out; Tony and Ziva find a mess inside. [To be continued.]

In the aftermath of Jenny's death, Assistant Director Vance searches for Franks, who escaped the diner after killing the fourth gunman. Meanwhile, Tony and Ziva try to locate the one responsible, while dealing with the fallout of failing in their assignment to protect the Director. The trail points to a former hitman called Natasha, who Jenny failed to assassinate in Paris nine years previously while on an assignment that she and Gibbs were working on together. Since Gibbs killed Natasha's lover, Natasha has returned to the U.S. seeking revenge. Natasha, who never saw it coming, is killed by Franks, after Gibbs set a trap for her at Jenny's house. Gibbs burns down the house to cover up Jenny's death, making the public believe she died of smoke inhalation. In the fallout of Jenny's funeral, newly appointed Director Vance shreds a page from his personnel file in the Director's office and terminates Ziva's liaison status (sending her back to Israel), reassigns McGee to the cyber crime division, and sends Tony to the USS Ronald Reagan. Vance then gives Gibbs personnel files for his new team members.

The Metro PD finds the body of an 18-year-old Marine who had grown up in the same hood where he died; the Gibbs team investigate with the help of Franks. They slowly assemble the picture, then a gentle social worker offers the last piece.

Gibbs's boat, which he gave to Franks, drifts, with two bodies aboard, into the Naval Station at San Diego. Vance and the team investigate. Franks and two relatives show up at Gibbs's house. The gang solve the case and make an arrest.

The body of an NCIS agent turns up in a bonfire on a beach near the US Naval Academy after celebrations just before graduation; Gibbs and company learn also about a rape of a sailor, and Gibbs goes to see Franks in Mexico. [Continued.]

Gibbs meets Paloma, the head of the Reynosa drug cartel in Mexico; he gets a ride to Washington, where he talks with Vance in code. Tony and Ziva arrest a bad guy, who then dies. Ziva attends a ceremony. Paloma meets Jackson. [Continued.]

Gibbs must take desperate measures to protect his loved ones with Paloma Reynosa still on the loose.

EJ and her team investigate yet another P2P murder; the victim is an NCIS agent from Norfolk; Gibbs and company pitch in, as does Franks. Kort, a CIA agent, spills in a briefing. Both Franks and EJ encounter the prime suspect.

Gibbs and Tony follow EJ and her team to a nearly vacant building; they find that the P2P murderer has killed Levin, seriously injured Cade, and kidnapped EJ; Gibbs pursues the suspect and EJ; he finds her, left to suffocate. McGeek traces a phone number to CI-Ray (Ziva's boyfriend). Ducky, with help from Gibbs, explains the changes in the MO of the killer. From Levin's left forearm EJ secretly removes a small object. Ziva tries to intercept Ray, but Cobb, the suspect, intercepts and kidnaps her; later, while Gibbs, Tony, McGee, and EJ are present inside a hotel room, Cobb arrives, enters, and surrenders, but he refuses to tell where he put Ziva. However, Abby provides clues to a place, where the gang plus Ray find and rescue Ziva, who gives explanations. Back at the HQ, Cobb escapes with two hostages; Gibbs and others follow; a confrontation ends the career of the P2P killer. The SecNav resigns, and his successor gives Tony a highly sensitive and classified task.

At a diner an unknown person with a drawn pistol approaches Gibbs, who deals with him; then Gibbs experiences flashbacks and fantasies, which Franks explains. The next day McGee announces a decision, then the gang gear up and head out.

A familiar face defends Gibbs in Parson's investigation. While the team tries to help Gibbs, they must solve the murder of a Navy SEAL.

Gibbs and company investigate the death of a woman with an ID card of a sergeant in the US Marine Corps; McGee finds that the real sergeant died in Afghanistan three years ago. Gibbs and McGee go to Kabul, sort things out, and do some good.

Tis the season to be hacking. In a Christmas letter to his father, McGee describes in detail a case in which he, Gibbs and the rest of the NCIS team investigate the hackers who are responsible for the Internet going down in the D.C. area.

The NCIS cyber case turns into a united global effort after evidence confirms "The Calling," an international terrorist group that recruits children through the Internet, has been purchasing German S-mines off the black market.

NCIS feverishly investigates a global terrorist group that is recruiting teens via the Internet, following a deadly bombing overseas that results in an emotional and surprising loss for the team.

Gibbs fights for his life after being shot by Luke Harris. Meanwhile, Agent Tony DiNozzo and CIA officer Joanna Teague travel to Egypt to take down The Calling.

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.

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.

EJ and her team investigate yet another P2P murder; the victim is an NCIS agent from Norfolk; Gibbs and company pitch in, as does Franks. Kort, a CIA agent, spills in a briefing. Both Franks and EJ encounter the prime suspect.

Gibbs's boat, which he gave to Franks, drifts, with two bodies aboard, into the Naval Station at San Diego. Vance and the team investigate. Franks and two relatives show up at Gibbs's house. The gang solve the case and make an arrest.

A traffic stop, a car crash, a Russian man with a pistol and false ID, a dead Navy chief petty officer, and the bloody letters NCIS all combine to require the attention of Gibbs and company; Franks lends a hand. Together they wrap it up.

Someone attacks a Marine corporal and leaves him to die, facedown in a snowbank in a park; Gibbs and company investigate. Mike Franks shows up and takes part; he and Gibbs sort it out and work it out. Tony and Jeanne encounter a problem.

The Metro PD finds the body of an 18-year-old Marine who had grown up in the same hood where he died; the Gibbs team investigate with the help of Franks. They slowly assemble the picture, then a gentle social worker offers the last piece.