'SPIES: The Epic Intelligence War Between the East and the West' by Calder Walton is a sweeping, meticulously researched examination of the espionage battles that have defined the modern world. It telescopes a century-long perspective on the covert struggles between the East and the West. Walton is a historian at Harvard University's Kennedy School of Government and one of the world's leading scholars on espionage.

His other books include the commissioned history of MI6, 'Empire of Secrets: British Intelligence, the Cold War and the Twilight of Empire.' He is also the general editor of the forthcoming multivolume 'Cambridge History of Espionage and Intelligence' to be published by Cambridge University Press.