Where did AIDS come from? Science has determined that the ancestor virus of HIV is found in chimpanzees. But how did it cross over to humans? Could AIDS have arisen as a result of Western medical intervention in Africa? This provocative documentary examines those questions in depth, and suggests that the notoriously insular scientific community deliberately thwarted efforts to find the answers. The film relies heavily on the testimony of investigative journalist Edward Hooper, whose 1999 book The River posited a link between HIV and a contaminated oral polio vaccine (OPV), which Western doctors fed to roughly a million people in central Africa between 1957 and 1960. Famously smacked down by the scientific establishment at a 2000 London conference on the OPV controversy, Hooper here receives corroboration from lab assistants who participated in the preparation of vaccines cultivated with contaminated chimp tissue. More importantly, doctors who for years denied authorizing the use of chimp cultures in Africa come forward, on and off the record, to reveal the truth. In a just world, this film would compel scientists to re-examine the evidence, but with billions of dollars in vaccine patents at stake and the prospect of devastating class-action lawsuits, the cover-up may continue. Science is, as one of the interviewees observes, "a very cruel culture," in which hypotheses exist only to be demolished by those with the facts -- or the power -- to debunk them. To those affected by AIDS, and denied access to the truth about its origins, that culture has been very cruel indeed.