In the months before he was arrested, allegedly on his way to carry out a plan to kill children at a local school, a 13-year-old boy spent hours alone in his bedroom.During the long, caffeine-fuelled nights in his home in Maryborough, 300 kilometres north of Brisbane, the boy was allegedly radicalised online.Last month, the Australian Federal Police told a parliamentary inquiry into youth radicalisation that the boy was exposed to extremist content in the "darker corners of the web".The boy was arrested at a service station, where police allege he was going to steal a vehicle to drive to a...