Searching for Sugar Man is a great documentary. (2012) 83 min.
An obscure Detroit singer-songwriter, Rodriguez, makes an album that speaks to people in South Africa as they are protesting apartheid. As his record flops here in the US, bootlegs of his songs become wildly popular in Capetown. The apartheid gov't forbids his "anti-establishment song" to be played on any radio station, and scratches that particular track on each and every vinyl record to prevent it being played - that is how much the inspiration of his song scares them.
Years later, two guys in the music biz try to find him. Nobody knows who he is (in the US) or anything about him (in South Africa). There are rumors that he killed himself onstage, but in fact, he is living in poverty in Detroit and working on a demolition crew. He and his 3 daughters go to Capetown where he does 6 sold-out concerts. At each concert, thousands of people stand and scream his name - that is how much they love him.
He had no idea.
tl;dr trailer: https://www.youtube.com/watch?v=KKXewWDh1og