This book explores the relevance of Sartrean existentialism to the contemporary socio-political landscape, with particular reference to his early novel Nausea and the concepts of bad faith and authenticity outlined in his major philosophical work Being and Nothingness. In an era where political authoritarianism has asserted itself so powerfully internationally and climate crisis has revealed the shortcomings of the political class so sharply, Stuart Sim argues that existentialism has much to offer as a worldview in addressing such issues. The sense of a world order falling apart connects us strongly to Sartres situation in the Europe of the 1930s and 40s, when fascism was in the ascendant and human rights under severe threat as a direct consequence. To read Sartres work through these phenomena is to realise the renewed importance of key existentialist concepts to the current geopolitical situation.