In Clements’s A Prince and a Spy (Pegasus Crime, Sept.), operative Tom Wilder probes the suspicious death of a British royal during WWII.

How did the Wilde series start?

I had a lot of stories to tell and characters I wanted to introduce to the world—particularly Tom Wilde. He was inspired by two Americans with close ties to Britain: James Jesus Angleton, a poet who attended an upper-class English boarding school, and later became chief of CIA counter-intelligence, and Conyers Read, a historian who studied at Oxford, wrote a history of Elizabethan spymaster Sir Francis Walsingham, and was involved in setting up the OSS, America’s wartime forerunner of the CIA. Wilde has things in common with both guys, but he is very much his own man.

How did you come up with the “Who killed the king’s brother?” plot for this book?

The death of Prince George, the Duke of Kent, in 1942 has fascinated me for many years. Very little was made of it at the time, and the plane crash that killed him has never been properly explained. Britain’s finest pilots were at the controls of a plane which was in perfect working order—and the plane had plenty of time to reach a safe height. So why did it crash into a hillside a mere 600 feet high? Knowing the history of the war at that stage, I believe I came up with a perfectly feasible answer to the riddle.

Without spoilers, can you discuss the historical basis for the theory that Prince George was murdered?

This is tricky, but I would just say this: in 1942, at the time of the duke’s death, the war was not going well for the Allies. Nor were things perfect in the East, where Hitler had failed to deliver a knockout blow against the U.S.S.R. With many in Britain, America, and Germany wanting a truce, the duke would have been the perfect candidate for secret peace talks with the Nazis. Other powerful forces, of course, would have wished him dead, thus killing off the hope of a treaty.

What’s the advantage of having your lead be an American, rather than a British intelligent agent?

That was very important to me. The books are centered on the University of Cambridge, which, in the 1930s, was a snobby place full of the children of the upper classes. It was also infamous as the breeding ground for the so-called Cambridge Spies—young men who embraced communism and infiltrated the secret services, betraying Britain and America to the Soviet Union. I wanted my man to be an outsider, looking upon the English class system with a modern, critical eye.