This Oscar winning film is the first of two documentaries made by this director about worker's struggle for better conditions in the US context. This one is about the coal mining industry. The coldness and exploitative greed of owners which extends to murder is graphically depicted. The simple lesson is that some people will do anything for money and the clash is almost Darwinian. The capacity of one group of people to treat another as things (in the Rwanda massacres one tribe was labelled as "cockroaches") seems inbuilt in human nature, alongside the better faculties. The film owes much of its power to the country music specifically related to coal miner's life. This film belongs to the era when socialism was alive enough to be kicked.