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. Ziva gets the bad guy, his controller, and the evidence.
A former petty officer and federal prisoner, convicted of murder and bank robbery, escapes and contacts Fornell, who, with Gibbs, caught him. Fornell contacts Gibbs, who contacts Jen, who temporarily reinstates Gibbs. The team solve it.
Gibbs returns to remain indefinitely. A bloody, screaming woman (a Navy lieutenant) disappears from the rear of her stolen SUV; Gibbs and company investigate. Abby and Ducky help. The gang find the victim, the bad guys, and their story.
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.
A real-estate agent discovers the decomposing body of a Marine; Gibbs and company investigate. The Marine disappeared six months before; the body had been buried and exhumed. The team find three fiancées, a fourth woman, and the answers.
On Halloween the Gibbs team investigate a gunshot wound to a Marine and the kidnapping of his 7-year-old daughter. The kidnapper demands $100K, and the mother disappears. The gang find the mother, the bad guys, the girl, and the answers.
A Marine colonel dies in an explosion when he hits a golf ball at the Army Navy Country Club in Arlington; both the NCIS and the Army CID investigate. The joint team later find a fourth bomb, and Ziva disarms it, but they lose the bad guy.
At a hotel in Washington, a homeless hero Marine veteran falls to his death, and a maid finds the body of a 14-year-old girl. Gibbs and company investigate; Ducky, Abby, and McGee help, Lee goes undercover, and the team find the bad guys.
At 02:30 Tim's little sister, Sarah, shows up at his pad, saying that she thinks that she's killed someone (a Navy seaman). Gibbs and the gang find much circumstantial evidence implicating her, but they solve it and nab those responsible.
While replacing a furnace at Quantico, workers find a smoked body in the chimney; Gibbs and company investigate. Fornell shows interest, saying that the victim was a serial killer. Abby enables Gibbs and Fornell to confront the real killer.
While testing a robotic driverless SUV, a woman Navy lieutenant becomes trapped inside it, and she dies of carbon-monoxide poisoning; Gibbs and company investigate. McGee suggests murder, Abby has trouble, and the gang find the bad guy.
A woman Marine first lieutenant, born in Kuwait, who has served in intelligence, returns from Iraq and turns up dead in a motel room in a small town; Gibbs and company investigate, with both help and resistance, and find three bad guys.
Responding to a call, Gibbs and company find the body of a Marine major in an underground utility vault beneath a street intersection. Abby finds the cause of the death, and Gibbs and the gang find Sharif, the bomber from the golf course.
An illicit arms dealer reveals a deal involving another dealer; McGee and Ziva tail a key player, who dies. Ducky impersonates the dead man and meets the Frog, whom Jen has long pursued; much good results, but the gang do not get the Frog.
A couple find the body of a Navy petty officer in an abandoned restaurant in Georgetown; the Metro PD calls and helps the NCIS; Gibbs and company investigate. Messages leave clues leading to an exclusive nightclub. The gang figure it out.
A Navy lieutenant, a member of an international nuclear-inspection agency, asks Gibbs to solve the officer's own murder because he knows that someone has exposed him to radiation poisoning. The gang succeed, and they arrest the bad person.
A family crypt in a mausoleum explodes when unsealed; Gibbs and company investigate; Ducky says that parts of at least three skeletons occupied the vault. The team identify and check out a suspect, and Gibbs and Hollis get a major surprise.
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.
An explosion kills two NCIS agents from another team; Gibbs and company investigate; feelings and emotions run high. Ducky and Abby find evidence suggesting opposite answers, but the gang resolve the problem, and they solve the case.
Gibbs and company investigate a crime scene; while doing so McGee recognizes that key details duplicate details in his second novel, still unfinished and in progress. The gang find two bodies; they eventually find the delusional bad guy.
Jen meets with an informant about the Frog, but someone kills the witness; Gibbs and company investigate. Jen obsesses about catching the Frog. Abby produces many answers; although the gang persist, they find a surprise but no Frog.
A blind photographer takes a picture; his assistant sees the body of a sailor in the background, and she calls the NCIS; Gibbs and company pursue. The gang find a second body, which leads to another crime, three solutions, and the bad guy.
While Jen attends a conference in Paris, Gibbs serves as the acting director. When a taxicab delivers a fare to the NCIS headquarters, the passenger, a Yemeni, is DoA; the gang investigate. Jen diverts to Moscow, and many answers emerge.
Jen returns from Paris; at home she finds a curious sight. All NCIS agents in Washington must take polygraph tests; Gibbs and the gang look into that. Tony and Jeanne deal with an injured pedestrian; Jeanne introduces Tony to her father.