Backstage at the Convention Center, Washington, DC, during preparations for a fund-raising concert to benefit the Hero Comfort Foundation, an explosion kills two men: a janitor and a volunteer worker, who was also a Navy petty officer first-class; Gibbs and company investigate; the fire chief said that the source of the detonation is a part of the warhead of a WW2-era torpedo. McGee and Ellie speak with Mannheim Gold, the apparent target of the explosion; during questioning his agent shows up and starts running his mouth. Mannheim goes home with Tony, then to a sudden gig. The concert takes place at a different venue. Abby deduces who planted the bomb, McGee digs up that man's past, and Gibbs and the gang put the pieces together; they figure out the reason for the bomb and the change of venue, then Gibbs and Ellie find the bad guys and a bunch of loot. Palmer experiences some good ups and a disappointing down.