Marion Cave Rosselli is remembered as the 'perfect companion' of the Italian Antifascist leader Carlo Rosselli, assassinated in Paris in June 1937. But little is known about the young English student fired with revolutionary enthusiasm who moved to Florence in 1919, witnessed the violent march of fascism to power and thereafter became a resolute adversary of the Mussolini dictatorship. Based on a wealth of little-used private and public archives, this biography retraces her journey from a modest home on the outskirts of London to the first underground Antifascist opposition in Italy, from the prison island of Lipari to exile in Paris and the United States. It reveals the social, cultural and existential factors which underpinned her unflinching political engagement alongside her husband. It also highlights the many challenges faced by Antifascist women within a highly patriarchal movement by bringing to life the figure of a woman who challenged the traditional division of labour within the family and struggled to carve a political role for herself. Reconstructing Marion Cave Rosselli's experience in relation to the multiple political, social and cultural worlds she moved in, this book broadens our understanding of the Antifascist movement and offers a richly detailed portrait of a time full of hopes, anxieties and disappointments.