After an unknown female assailant kills two men disguised as Sherriff's deputies in front of Callen's home, the NCIS team gets a new lead in the ongoing mole investigation. Also, Nell visits a prison to interview an inmate withholding information on the department's leak.

After a Navy reservist is killed while protecting a city councilman, Sam is sent undercover in a private security firm with links to several criminal organizations. Also, Callen and Anna discuss the next steps in their relationship.