A valuable study of five British scientists of the interwar years-including J.D. Bernal, J.B.S. Haldane and Joseph Needham-and the evolution of their left-wing, often communist political views. The author, an American historian living in England, relates biography, social conditions and scientific thought as the background of political attitudes. A readable, serious effort at collective biography, full of telling quotes, written from an avowedly sympathetic perspective convinced of the relevance of earlier scientific socialism to Britain's present condition. The book is, however, marred by an extraordinary British insularity: Were these men really so isolated from their continental colleagues at that time?