While the team is on protective detail for the Chief of Naval Operations, McGee spots an argument taking place in an alleyway. He shoots one of the men, who he believed was aiming a gun at him. The deceased turns out to be a D.C. Metro police detective. When the team is unable to find any weapon or bullets left behind by anyone other than McGee, it appears that McGee may have made a probie mistake. McGee begins to doubt himself but Gibbs is suspicious of the detective's meeting, which took place that night. After speaking to the decedent's partner, the team realizes that McGee's story may be more accurate than any of them thought.