How do normal people become able to torture others? In order to explain this puzzling social phenomenon, we have to take secrecy – the characteristic trait of modern torture – as the lynchpin of the analysis. Following Georg Simmel’s formal analysis of the “secret society”, the contribution reconstructs structural and cultural aspects of the secret society of torturers that generate social processes that allow its members to behave extremely violently, forcing individuals to turn into torturers. The contribution argues that the form of social behaviour that we call torture is socially shaped. It goes beyond social psychology to develop an explanation from the perspective of relational sociology.