While investigating at a port, Tony and Ziva encounter unexpected criminal activity; they become trapped inside a shipping container. Gibbs and McGee, with the help of Ducky and Abby, find not only their teammates but also the bad guys.
In the Shenandoah National Park a bear eats a part of the body of a murdered Navy petty officer; Gibbs and company investigate. A woman companion has disappeared; the gang deduce her identity. Ziva finds her, and Gibbs nails the killer.
A student, Kody, seizes control of a room and six classmates, threatening to detonate a bomb; the NCIS and others respond. Gibbs walks into the room and confronts Kody, who demands to see his mother, said to be dead. The team work it out.
A boy at play on a frozen pond sees the body of a man below the surface. Gibbs and company investigate; they find three more bodies. The first was a Marine; the others were gang members. The team figure it out; Gibbs provides a solution.
Tony and Ziva go to the home of a woman Navy lieutenant and cryptologist; they find her dead, apparently by suicide. Gibbs and the gang find evidence of murder instead; after pursuing the wrong clues, they lose a mole but catch the killer.
A couple enter a room at a Navy Lodge and find bloody human body parts; the Gibbs team investigate. Gibbs and Ducky agree that the scene was a setup. An imbalanced former boyfriend stalks Abby. The gang chase the clues and figure them out.
A suspect collapses and dies while in the custody of Ziva; she becomes a suspect rather than an investigator. The team investigate. Then the director disappears, and her driver dies. Ducky clears Ziva, and Gibbs and his gang rescue Jen.
Aboard a Turkish-flag cargo 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 recognize him.
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. 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.