It's summer on ABC Radio National so we're bringing you some of your favourite stories from the year gone by. Today, we're giving you a peek behind the curtain of secretive extremist subcultures. They're in our backyards, but most of us know next to nothing about them. We speak to a journalist who delved down the rabbit hole of the history of conspiracy theories in Australia.  We also look into the tradwife subculture, and speak to a young mum who says the movement has been co-opted by alt-right radicals.  And a de-radicalisation specialist explains why young people are sucked into extremism online.