Italian philosopher Giordano Bruno (1548–1600) investigates an impossible murder in Parris’s Treachery, (Pegasus Crime, Dec.).

Where did the idea for the Bruno series come from?

I first read about Bruno when I was at college and immediately thought his life was so remarkable—I knew then that I wanted to write a novel about him. But he did so much that I couldn’t work out the way into it, and put him aside for about 15 years. Then I came across a book by a historian who argued that Bruno had worked as a spy for Elizabeth I’s government while he lived in England, and that was the spark for the series—I realized I could indulge my love of spy and detective fiction and tell his story at the same time.

In what ways have you departed from what is known about the real Bruno?

At first, I tried to stay close to what was known about where Bruno traveled and who he met, but I quickly realized that I would have to take some license for dramatic effect. I try to keep his character true to what we know of him—the real Bruno was, by all accounts, extremely charismatic, infuriating, and a person of great intellectual courage, so I’ve tried to bring out those attributes.

What does having your lead be a foreigner do that you couldn’t have done with an English lead?

Bruno spent half his adult life in exile, and I’ve always found that a fascinating perspective. He’s always the outsider—in England that would have been particularly noticeable from his looks, and we know from his own writings that he encountered a lot of prejudice. But all the best detective heroes are outsiders—it allows them to observe with a clearer eye, and Bruno has allowed me to make some oblique commentary on the English and the way we treat foreigners—which, at the present time, is often not a lot more enlightened than it was in the 16th century.

What do you believe is the biggest misconception about the Elizabethan period?

We hear a lot about the glories of Elizabeth’s reign—the colonization of the New World, the defeat of the Spanish Armada—and because the Church of England has lasted for over 400 years, it feels inevitable. I don’t think people realize how precarious her reign was, and how many plots against her were only just foiled. In Europe, they called her government the Protestant experiment, and it could so easily have been no more than a brief interlude, if any of the assassination or invasion attempts had succeeded.