Review: In search of Klingsor by Jorge Volpi (Fourth Estate, £17.99) This gripping book is a novel, but is suffused with so many threads and facts of real life that it is hard to tell where reality breaks off and fiction begins, writes Philippa Logan.

The subject matter is thrilling -- the failed attempt to kill Hitler in July 1944, and the desperate work of international physicists, on each side, to develop an atomic bomb. Behind this is the quest of a young American physicist, commissioned to uncover the identity of 'Klingsor' -- Hitler's advisor on the atom bomb, who decided which projects were funded and which were not.

The book is fascinating on many counts. It is a powerful history of the men of science during the war, and of the power that they held over their political masters. It follows the development of maths and physics, and the growth of friendships and animosities between those physicists as it becomes clear to what use their research could be put.

The young American in the book, Francis Bacon, meets many of the most famous scientists of the time -- Heisenberg, Schrdinger, and Bohr, for example -- and we are privy to their conversations.

Between them, Bacon and the mathematician Gustav Links, who was involved in the failed assassination attempt, pursue the identity of Klingsor with as much vigour as a detective hunting down a murder suspect -- and the tension in the book is every bit as relentless as if this were a murder inquiry.

Even Links's retelling of the attempt on Hitler's life is gripping, despite the reader knowing in advance that the plot will not succeed.

There is a love angle too, but this is no mere sub-plot, put in to appease a publisher. The woman with whom Bacon becomes involved is an enigma in herself and it is not at all clear what her motives are. Her participation adds to the sense of urgency in the search for Klingsor.

I cannot recommend this novel too highly. It is not a book to be read lightly, for the themes are too important and interesting, but it rewards the reader with the facts of history and science during the Second World War, delivered through a compelling narrative.