Japan's notorious germ warfare Unit 731 and its horrific human experiments represented one of the most heart-wrenching chapters in WWII. What gave rise to such insanity running amok?  The documentary "Death Factories," produced by RT, takes viewers back to the 1930s, exposing the history behind: When the delusion of "Japan's exceptionalism" married with an obsession over biological weapons – and when science was completely perverted into an instrument of mass killing – the gates to horror were thrown wide open.