NCIS is called in to investigate the murder of a naval officer at Little Creek Naval Base following an anonymous tip-off. McGee manages to track the tip-off to Langley, suggesting that the CIA have been spying on the base. Gibbs and Kate follow the tip-off, coming across a witness who leads the team to several possible suspects. At first the murder seems to be tied in with the R&D work the officer was involved with, but the team soon begins to suspect a more domestic motive.