When a Marine is found impaled on a tree stump, Gibbs and his team begins a search for the weapon and the murderer. The case leads them to a pawn shop known to deal in stolen military weapons where they discover an undercover ATF agent Melinda (guest star Bellamy Young) who’s also hoping to also crack the case. Gibbs brings her into his scheme to meet with a local militia leader looking to buy illegal weapons, but when the plan goes awry, it is revealed Melinda is not who she seems to be.