Warren Lerner’s 1970 biography of Karl Radek may be the only English language biography of this once-famous, now-forgotten Bolshevik leader. Karl Radek, born in 1885 and died in 1939 (possibly) was intensely disliked by most people he knew. Rosa Luxemburg detested him. So did Zinoviev, and Trotsky too later in life. He was impulsive, unprincipled and nasty, as one can see when reading his attacks on Karl Kautsky or the Georgian Social Democrats. And yet — he rose to the very heights of the Communist International and managed to stay there long after most of his comrades were killed off by Stalin. Why? It seems that he was very smart, and wrote well and in several languages. He was often right — for example, in cautioning the German Communist Party (KPD) against the adventurist attempts at revolution that nearly wiped the party out in its early years. He also understood before most that the Chinese Communist Party was about to fall victim to Chiang Kai-shek’s Kuomintang which was being courted at the time by the Comintern. He could also be incredibly wrong — including embracing the idea of “national Bolshevism” in Germany, trying to find common ground between the KPD and the emergent far-right parties, including the Nazis. Lerner, who passed away in 2007, was a very good writer and tells the story well and clearly. His final chapter which focusses on, among other things, Radek’s Jewishness, is of particular interest.