The story of Hooligan Sparrow
7 March 2016 Last updated at 23:51 GMT
Chinese filmmaker Nanfu Wang was intimidated and threatened by authorities in China while filming activists involved in protests over child sex abuse allegations in 2013.
Her film, named Hooligan Sparrow after one of the activists, was smuggled out of China and premiered at the Sundance Film Festival.
This is the story of their struggle and how she finally made this film.
Filmed and produced by Anna Bressanin