This book builds a theoretical perspective for explaining what security remains after the security event. It studies in detail the evolution of security thinking before, during and after the 2011 terrorist attack in Utøya and Oslo, Norway, tracking the political discourse and the institutional reactions in order to form a theory of ‘terror and disenchantment’. It develops a general theory of security that contributes to ongoing debates on non-military security, asymmetric warfare, ontological security and human security. It revisits the nature of terrorism, the sense of its practice and re-conceptualises the way practice of counter- and anti-terrorism are embedded in social, cultural and national consciousness.