Japan's notorious germ warfare Unit 731 and its horrific human experiments represented one of the most heart-wrenching chapters in World War II. 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 a so-called "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.