Within 30 miles of Washington, DC, eight kids in Navy and Marine Corps families have suddenly become badly ill, requiring treatment in ERs and ICUs; Gibbs and company investigate; Carol, of the Naval Medical-research Center, joins the effort; immediately the number of sick kids grows to 14, then 19, 23, 28, and 34, and none of them responds to treatment. Duck announces the first fatality, who was a veteran of Vietnam, then he describes the cause of death and the treatability in the kids. Abby says that she has misidentified the particular nature of the illness, so she, Jimmy, and Carol keep working, and they eventually nail it. Abby gives Jimmy a lecture about kindness, optimism, and parenthood. Then the gang identify an international traveler who in many places has recently encountered many kids and the fatality. Meanwhile Vance has three tense chats with his estranged father-in-law and then a nicer one.