Lone wolf terrorism

From Mohammed Bouyeri assassination of Theo van Gogh to Anders Breivik' Utøya massacre, to the most recent Jihadist and far right attacks, violence is spreading throughout Europe increasingly in the form of lone wolf terrorism. But who are lone wolves? What is their relation with group based terrorists? Is their violence the fruit of some mental disease? Or there is a precise radicalization path pursued through an ideological indoctrination? And, if yes, how can this process be stopped at the time of internet and globalization? This sociological study runs into the depth of lone wolves terrorist action, through the analysis of their life, personalities and motivations, to find out how even apparently ordinary people may turn into merciless killers against their own society.