In recent years, the study of German-speaking émigré scientists in Britain after 1933 has received considerable scholarly attention, shedding light on this previously often overlooked facet of the British history of science. Kenneth D. McRae's monograph Nuclear Dawn: F.E. Simon and the Race for Atomic Weapons in World War II contributes to this area of study. Focusing on Franz (Francis) Simon, McRae explores the life and scientific work of one of the most important of these émigrés. Born in Berlin in 1893, Simon trained as a physicist and subsequently became widely known for his pioneering work in low-temperature physics and, especially during the Second World War, uranium separation.

For the most part, McRae's book is an orthodox biography of Franz Simon that largely adheres to a chronological structure and is divided into eleven chapters. After the first chapter has focused on Simon's and his wife Lotte's formative experiences of the First World War, the ensuing three chapters follow them through three important stages in their lives, from 1920s Berlin to Breslau, where Franz Simon was appointed to a chair at the local university. Chapter 4 deals with the Simons' emigration to Oxford, where Simon found employment in wake of Adolf Hitler's appointment as German chancellor and the subsequent implementation of legislation that excluded Jewish scientists like him from working in German academe. Chapters 5 and 6 then focus on the Second World War and Simon's contribution to the making of the first atomic bombs in the joint Anglo-American-Canadian Manhattan Project. The subsequent chapter attempts to offer an explanation as to why Nazi Germany failed to develop a working atomic weapon, before the next one looks at Simon's work in the early postwar period. Chapter 9 focuses on the Klaus Fuchs atomic espionage case. The following part explores the extent to which Franz Simon re-established contact with former colleagues inside Germany and others who, like him, had been forced to leave Germany because of National Socialist policies. Nuclear Dawn concludes with a final chapter in which McRae explores Franz Simon's professional travels and the Simon family's holidays in the postwar period, ending with Franz's death in 1956.

In some ways Kenneth D. McRae's biography is a curious book. On the one hand, the author had access to primary source materials that no other researcher has used before him. On the other hand his study often fails to place these sources adequately within their wider historical and historiographical contexts. Instead, McRae offers for most part a close reading of these documents. And this is one of the major weaknesses of McRae's book. Existing key historiography of émigré scientists in Britain (e.g. Paul K. Hoch's pioneering work, or Sabine Lee's edited selected correspondence of Rudolf Peierls) or of nuclear history more widely (e.g. Ferenc M. Szasz's work on British scientists and the Manhattan Project, or Andrew Brown's biographies of Sir James Chadwick and Joseph Rotblat) is absent from Nuclear Dawn. Similarly, recent work on German-born refugee scientists who emigrated to the United States and played an important role in the Manhattan Project, such as James Franck (Jost Lemmerich, Science and Conscience: The Life of James Franck (2001)), might have offered an insightful comparative angle on Simon's experience. The lack of engagement with recent historiography becomes particularly evident in Chapters 7 and 9. In Chapter 7, ‘an essay in comparative analysis of the five nuclear programmes that were active during the war year’ (p. 137), Cathryn Carson's work on Werner Heisenberg, for example, is omitted. Chapter 9, which deals with the Klaus Fuchs atomic espionage case, relies on such studies as Robert C. Williams's almost thirty-year-old biography of Fuchs and Brian Cathcart's popular history of the British nuclear weapons programme. By contrast, Michael S. Goodman's recent work on the spy case is absent.

Overall, Nuclear Dawn is slightly disappointing and does not fully deliver on the promise outlined in the book's subtitle. While McRae adds some new primary source material to our knowledge of German-speaking émigré scientists in Britain during the era of the Second World War, his treatment of these sources largely remains underdeveloped, and he tells a broadly familiar story. Nuclear Dawn would have benefited from a rigorous grounding of the source material in both a clearly defined conceptual framework and the recent historiography of the subject matter, as Charles Thorpe, for example, has done in his seminal biography of J. Robert Oppenheimer.