The book offers the first comprehensive history of "Giustizia e Liberta" and its transnational networks. This Italian antifascist revolutionary group operated both in emigration and underground, offering radical responses to critical questions of interwar Europe. How to understand and fight fascism? How to rethink politics in the maelstrom of crisis that shook Italian and European society in the 1930s? How to design a new post-fascist order out of the ruins of the Great War ? To answer these questions "Giustizia e Liberta" - founded by Carlo Rosselli in Paris in 1929 and disbanded in 1940 - developed several revolutionary projects and linked socialist and liberal traditions in innovative ways, inspired by French and European culture. Their debates focused on fascism as a product of a post-1914 civilizational crisis and a key political, social, cultural phenomenon of the interwar period. To struggle against its enemy, the group aimed to go beyond the Marxist notion of class and to assert different concepts of nation and Europe, while elaborating lucid comparative thoughts on tyrannies. The book traces the group's trajectories and debates in the political and intellectual history of twentieth-century Italy and Europe, and follows its profound and multifaceted legacy to the present.