While the NCIS team investigates the cause of a hit and run accident that resulted in the death of a Petty Officer, Gibbs searches for a way to clear a Navy Hospital Corpsman, who has served two medical tours in Afghanistan, after she's indicted for illegally providing medical aid to the victims of the crash, even though the surviving victims swear by her life-saving techniques.

Gibbs and the team work to clear the name of retired Marine Sergeant John Ross when cyanide is found in one of the hundreds of care packages he sends to active-duty Marines.

After NCIS arrives at a Halloween crime scene, Torres recognizes the victim as a friend from federal law enforcement training. Also, Jimmy thinks his lab is haunted by ghosts after objects keep mysteriously moving.

Director Vance is notified by the Pentagon that the nuclear submarine Gibbs and Bishop are aboard to conduct a murder investigation has gone radio silent.