This is London from an exhilarating, rarely seen perspective. With knife violence rising, social activist Mac creates BikeStormz, a movement for kids across the city to express themselves beyond any threats of violence. Groups of young people glide through the capital on their bikes, doing wheelies, tricks and death-defying acrobatics, but as they come together and find ways to express themselves through biking - the kind of liberation that surfers and skateboarders eulogise - they are challenged with the threat of arrest by the police and accusations of antisocial behaviour.