After a mysterious illness strikes children from military families, Gibbs and the team investigate the cause. Meanwhile, Abby and Jimmy partner with the Naval Medical Research Center to determine the strain of illness, ...
A marine's body is found inside a new home. The body had been buried, then dug up, and put in the home. His 2 fiancées have been receiving letters from him for the past few months. Did one of them get wise?
A homeless veteran falls from a hotel room into a party with a lot of high ranking officials. During the investigation they discover a body of a young girl who had apparently been assaulted by the veteran.
Mc'Gee's restless writing night turns nightmarish when his under-age sister Sara turns up, with bloody hands and a constantly changing story. She's drunk and never could hold her liquor, but is the part she murdered someone without remembering who or why also imagined, or a recollection from a 4 hours black-out? Alas, the fatally stabbed corpse which NCIS investigates on Waverly, her college campus, is that of USS Enterpise seaman Jeff Petty, who dumped Sara for a cheerleader a year earlier. Her cellphone on the corpse puts Gibbs on that trace, and betrays Tim's (dis)...
A body falls out of a smoke stack on a Marine base. The FBI tries to take over the investigation when the body is linked to a serial killer who had vanished. Ducky and Gibbs discuss the source of their conflict.
When a high-level Marine intelligence officer is found murdered in a small motel room, the NCIS team must find the person who murdered her. 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.
Some maintenance workers open a crypt, and it explodes. They find some skeletal remains in what was supposed to be an empty unit. After Ducky determines the remains belong to multiple skeletons, NCIS must track down a serial killer.
Just as Ducky is about to perform an autopsy, his patient wakes up on the table. NCIS investigates Gibbs finds out an old friend has a personal stake in the matter. Tony's relationship hits a cross roads.
Cassidy's team gets a tip on a terrorist plot, when they investigate. The agents are killed by a suicide bomber. Cassidy teams with Gibbs' team to find out who set up her agents. Ducky and Abby find evidence that seems to contradict each other. Gibbs reveals a secret to his team that affects some of his agents.
While processing evidence from a crime scene, McGee is shocked when he discovers a link to his newest/unfinished novel. When the team finds 2 bodies, the race is on to find the killer and his link to McGee's work. McGee finally admits he based his characters off his co-workers.
Director Shepard returns and finds evidence that someone from her past may still be alive. NCIS must undergo polygraph tests, ordered by Homeland Security. While Gibbs investigates who ordered the tests, Tony and Jeanne face a crisis together.