This remarkably ambitious book tells the story of the great social and political catastrophe that enveloped Europe between 1914 and 1945. In a period of almost continuous upheaval, society was transformed by two world wars, the Russian Revolution, the Holocaust, and the rise and fall of the Third Reich. Combining a powerful narrative with profound analysis, acclaimed historian Robert Gellately argues that these tragedies are inextricably linked and that to consider them as discrete events is to misunderstand their genesis and character. Central to the catastrophe, of course, were Lenin, Stalin, and Hitler, and this book makes use of recently opened Russian and German sources to explain how these dictators’ pursuit of utopian—and dreadfully flawed—ideals led only to dystopian nightmare. In a groundbreaking work, Gellately makes clear that most comparative studies of the Soviet and Nazi dictatorships are undermined by neglecting the key importance of Lenin in the unfolding drama. Rejecting the myth of the “good” Lenin, the book provides a convincing social-historical account of all three dictatorships and carefully documents their similarities and differences. It traces the escalation of conflicts between Communism and Nazism, and particularly of the role of Hitler’s anathema against what he called “Jewish Bolshevism.” The book shows how the vicious rivalry between Stalin and Hitler led inescapably to a war of annihilation and genocide. The reverberations of this gargantuan struggle are felt everywhere to this day.