In May 2014, 22-year-old Elliot Rodger shot six people and took his life in a campus shooting in Santa Barbara, California. He left a long memoir documenting in detail the journey he made from childhood to his ‘Day of Retribution’. An analysis of this text shows us that Rodger was not someone who communicated easily in offline contexts, but that he lived an intense online life in which games, movies and misogynist platforms, known as the ‘Manosphere’, figured prominently. It was in this online world that Rodger constructed a worldview in which his lack of sexual experience became translated into an acute ideology of victimhood. The women who rejected him became enemies and criminals, as did the men who were more successful in dating these women. Rodger, in other words, constructed a logic of action in the online world, leading to what he saw as justified revenge and punishment. After the killings, he himself, in turn, became an online icon in the Manosphere, a template to be followed. This analysis shows us the complex interactions between online and offline spheres of knowledge and action, in new types of knowledge-focused communities often operating ‘below the radar’.