Acting on a report of shots fired, the Metro PD finds the body of Marine Pfc. Emilio Salazar; Gibbs and company investigate. Salazar, 18, had grown up in the same neighborhood where he died; he enlisted four months ago, and he was scheduled for deployment next week; someone at the scene wrote Gibbs's Marine Corps service number in blood. Salazar had a criminal record since age 12; all his offenses were juvenile and gang-related; his body bore gang tattoos. Ducky says that Salazar died slowly after a single round to his chest, and that machine-gun fire strafed his body six hours postmortem. Gibbs calls Franks to Washington, DC, to help find someone; Franks says that Colombia was a long time ago. Gibbs and Franks chase the leads and question the sources; they feel puzzled, but they continue to fit the pieces together; finally they get the rest of the picture while speaking with a gentle, kindly former-Vista volunteer neighborhood social worker.