One of the most compelling episodes of twentieth-century Russian literature involves the epistolary romance that blossomed between the modernist poets Marina Tsvetaeva and Boris Pasternak in the 1920s. Only weeks after Tsvetaeva emigrated from Russia in 1922, Pasternak discovered her poetry and sent her a letter of praise and admiration. Tsvetaeva's enthusiastic response began a decade-long affair, conducted entirely through letters. This correspondence - written across the widening divide separating Soviet Russia from Russian emigres in continental Europe - offers a view into the overlapping worlds of literary creativity, sexual identity, and political affiliation. This book presents the first full account of this affair of letters and poems from its beginning in the summer of 1922 to its denouement in the 1930s.