macarthur foundationm, cmitted to building a more just, verdant and peacful world. captioned by media access group at wgbh access.wgbh.org >> for more on this and other "frontline" programs, visit our website at pbs.org/frontline. ♪ ♪ frontline's, "death is our business" and "love, life and the virus" are available on amazon prime video. ♪ ♪ ♪♪ you're watching pbs. ♪♪ ♪♪ ♪♪ (dramatic music) (siren wailing) (train engine rumbling)