After the body of a thief is found in a Marine's house, NCIS discovers the calling card of a terror group Delilah and the Department of Defense have been tracking.

DiNozzo is partnered with his girlfriend ATF Special Agent Zoé Keates after evidence reveals that the murder weapon in an NCIS case was originally purchased for the controversial ATF sting operation "Operation Fast and Furious." Also, Anthony DiNozzo Sr. returns to town for a special dinner to meet his son's girlfriend.