Norwegian filmmaker Kyrre Lien began researching online commenters on Christmas Day 2014. “I became fascinated by how much hate and ignorance people were writing in the comments section of a news site,” he says, “so I began looking at people’s profiles, trying to work out who they were. Many seemed quite normal. They had families and looked like nice people, but the comments they were writing in a public space were so extreme. There was a disconnect.” And so began Lien’s three-year journey into the lives of some of the internet’s most prolific online commenters, now the subject of a documentary, The Internet Warriors.