About the book

I grew up watching classic war films and reading the great Sixties and Seventies thriller writers; people like Jack Higgins, Alistair MacLean and Frederick Forsyth. I would say that Day of the Jackal, The Eagle Has Landed and The Guns of Navarone were the three key influences on this book. I've always wanted to be a writer and those were the kind of books I wanted to write; exciting, but literate and knowledgeable too.

The James Bond books were also a huge influence - I think it's been forgotten how well-written and grounded in reality they were. Bond is a World War Two veteran in the books, and the details of the development of British intelligence during that period are very true to life. Fleming was also immensely knowledgeable about the history of the Soviet spy agencies - the details of Rosa Klebb's pre-war background in 'From Russia With Love' got me reading a lot more about the development of the two competing Soviet security branches, NKVD and GRU (Military Intelligence), which made me realise that there was as much of a 'Cold War' in the Thirties as the Fifties.

I had the idea many years ago, when World War Two was still quite fresh in people's memories and the Cold War was still at its height. The more I read about the relationship between Britain and the Soviet Union during the war the more I realised that, in espionage terms, they were sworn enemies who'd signed a temporary truce.

We tend to think of the Cambridge Spies (Philby, Burgess and Maclean) as existing in the post-war era because that's (arguably) when they did most damage. But they were recruited in the 1930s and were active during the war. And on the other side, there were plenty of people who realised the true nature of Stalinism. They wanted to expose it, and certainly didn't want to see Soviet Russia become any more powerful than she already was.

At the same time, you have the final stages in the creation of atomic weaponry. Scientists all over the world were inching towards the key discoveries that opened up a new era in human history - and changed the way we view warfare forever...

I thought it would be fascinating to explore all this through the character of a Soviet nuclear physicist who had made discoveries that put him at the head of the search - but had become so disillusioned with the aftermath of the Russian Revolution that he was not only prepared to withhold his findings from the authorities, but was actually prepared to try to escape from Russia and work with the British.

Vlasenin is based to a large extent on Andrei Sakharov, who developed the first Soviet hydrogen bomb and later became a prominent dissident. He was a rising star during and after the war, but did his most significant work in the early 1950s. I've made Vlasenin older, a veteran of the First World War and a Hero of the Revolution - with a specific social context for his disillusionment.

The more I researched, the more I found out how many scientists there were like him - Enrico Fermi, who's mentioned in the book, escaped from Mussolini's Italy because he couldn't face the idea of his discoveries being used to help a fascist state become more powerful.

But if someone like that wanted to escape during the middle of the war, he would become the most wanted man of all time. Every country at war would want him and his knowledge. Although nobody knew exactly what atomic weaponry could do at that time, there was enough awareness of the theory, and its potential, to realise that it could make whichever country had the secret the most powerful in the world. Able to win not just the war, but the peace that followed.

It didn't turn out quite like that, but I thought the incentive would be enough to ensure every country with the resources to find and rescue this guy would make it a top priority - and wouldn't worry too much about keeping their allies 'in the loop'.

So 'the mission is a man', as in Saving Private Ryan. How his rescuers view Vlasenin, and how his relationship with them develops, is a key element of the book. But it also seemed to me that if someone like that did try to escape, he wouldn't keep his findings with him, just in case the worst came to the worst. So you have an extra 'Mcguffin' - the briefcase full of documents that are just as important as the man himself, and can't be left unaccounted for.

To me that seemed a classic old-style thriller premise; larger than life but believable and rooted in reality. Once I'd decided on that, all I had to do was find out as much as I could about World War Two espionage, nuclear physics, the history of the Soviet dissident movement... no wonder it's taken a while!

How did you go about researching the book?

Read a lot! First revisiting the classic thrillers I've mentioned, then the real-life stories of the men (and women) of the Special Operations Executive, which are often more incredible than anything you can find in fiction. Books like 'Eastern Approaches' by Fitzroy Maclean (who's often been identified as a possible model for James Bond) and 'Ill-Met By Moonlight', by W Stanley Moss, about the kidnap of the German commander of Crete and the long trek to get him safely off the island.

That became a key text when I realised that Turkey would be a possible escape route for Vlasenin, or a holding post if he should become captured. Istanbul in 1942 was surrounded by Axis-occupied countries but Greece had a burgeoning resistance movement. That took my research in a new direction, as I found out the bitter divisions between ELAS the Communist-influenced (I choose my words carefully, it's still a matter of debate and controversy) main resistance group and EDES, who were backed by the British but much more marginal. It was the only country where British troops ended up fighting members of a resistance organisation and it's still a source of bitterness.

But from a thriller writer's point of view it was a fascinating area of the war that I don't think many people are aware of, and raised the possibility of the Russians using their influence over ELAS to try to get Vlasenin back from the British. One tends to think of the resistance movements in the occupied countries as being united and uniformly pro-British, but it wasn't that simple and it adds an extra dimension to Rawlings' task.

I realised that I needed to visit these areas and talk to some people who remembered that era. So I spent a fascinating few weeks in Turkey, Bulgaria and north-eastern Greece. I can't express enough my gratitude to the British Council branches in Ankara, Istanbul, Sofia and Thessaloniki for their help and advice and the people I met through them. Sadly, there aren't too many alive now, but I spoke to some men who remembered the run-up to the first Greek elections after the war, when British troops encountered these huge ELAS legions coming in from the mountains. I said to one man: "They must have looked terrifying," and he replied: "No, they looked just like you and me." That quote came back to me constantly when I was writing the book.

There were many other books and sources that I drew on, some of which I struggle to remember now. But it made a fascinating picture overall. As I said, it's a thriller, an entertainment. But I also wanted it to be a genuine tribute to people who lived through those times and who all helped in a truly epic struggle. I hope I've succeeded, in part at least.

What are the dominant themes?

It's an ‘origin story’ of the nuclear age in many ways. The awesome power that Vlasenin holds comes with an awesome responsibility and I used that as a springboard to examine the broader issue of the responsibilities that scientists, and all people possessing extraordinary gifts, have to not let them be exploited in the service of a corrupt or cruel government. That's a dilemma that many of the characters have, in one way or another.

Closely linked to that was the idea of conflicting loyalties and the dangers of adherence to an extreme ideology, both of which I think have many contemporary parallels. You don't want to labour the point, but a key element of the book is that some characters have a vision of the world that transcends national boundaries - and ties of friendship.

The irony is that these characters are operating in a world that's about to be changed utterly. Despite their unique circumstances, the protagonists are essentially soldiers fighting a conventional war. Characters on all sides show immense bravery - because of a man whose knowledge will, in one sense, render individual courage in battle almost irrelevant. The espionage world is about to get even more covert and dirty and they don't realise it.

But the more I researched the more I realised that among all this bravery and elevated ideals the intelligence agencies on all sides were riven with internecine fighting and petty one-upmanship. The British intelligence establishment regarded the SOE with some distaste (Rawlings, a Northerner from a farming family, isn't immune from some snobbery from the 'gentleman spies') and didn't always trust them - and it was mutual. The NKVD were constantly jostling for power with the GRU. The German Abwehr was seeing its status slowly undermined by the Nazi-based intelligence agencies - and they all regarded the Italian SIM as an incompetent irrelevance - which was very far from the truth.

I felt the 'office politics' element of the book, as well as being absolutely rooted in fact, gave it a more human dimension. These guys experienced the day to day frustrations of work just as much as world-changing moments.

What are you working on at the moment?

Quite a few ideas. I'd like to do something in a different genre next, but I can definitely see myself returning to World War Two. There are just too many fascinating stories still to be told!