While serving as protection of the Chief of Naval Operations, all Hell breaks loose when McGee, having spotted an argument occurring in a darkened alleyway shoots one of the men. Things take a shocking turn when it's revealed that the victim is actually a detective who was working undercover for the Metro Police Department which has the victim's captain and the victim's partner arriving at NCIS with the intention of conducting their own investigation. The team believe that McGee made a mistake but Gibbs has his suspicions about the meeting that apparently took place....