In screenwriter Hayes’s debut, I Am Pilgrim, covert agent Scott Murdoch, aka “Pilgrim,” pursues both a lone-wolf bioterrorist and wrestles with personal demons threatening his own soul.

How did you convey so convincingly the mind and personality of a terrorist?

A hero can only be as good as the bad guy. I’ve read and traveled a lot in the Middle East, and I built on eyewitness accounts of horrific executions that would shape a boy’s character and beliefs if he watched his father die that way. These are the stuff of which nightmares are made. It occurred to me that the real problem would be when one terrorist deliberately decides to work alone, to stay under the radar.

What sustained you through the enormous research required for this book?

A natural and somewhat obsessive curiosity! I really loved the research. Also, the type of biological weapon used in the plot is now so accessible that a lone-wolf terrorist can use viruses as a weapon of mass destruction.

Pilgrims often undertake their journeys in search of enhanced understanding. What is your hero’s goal?

To catch a man who is pretty much a ghost. On a deeper level, I think many stories—especially thrillers—can be a journey to the heart of darkness. Scott Murdoch, possibly the best covert agent of his generation, carries a great deal of regret, pain, and mistakes from both his childhood and his professional past. He learns that if you want to be free, all you have to do is let go.

A moral dilemma—whether doing evil so that good may result is justifiable—smolders at the heart of this novel. How does Murdoch resolve this issue?

Pilgrim forged his moral system in the mean streets he had to walk as a covert agent. His time in Germany taught him that whatever evil was necessary to halt Nazism was overwhelmingly worthwhile in view of the greater good that would have resulted.

You seem particularly fond of your New York policeman, Ben Bradley, an ordinary American who does extraordinary things.

I love Ben Bradley—he’s what is good and decent in the world, like the frontier resilience and resourcefulness Americans and Australians share. I got to know Australians well working on the Mad Max franchise with director George Miller. I’ve observed similarities, very deep down, between Australians and Americans, a self-reliance, an individualism, a capacity to take things into their own hands. Ben came out of heartbreaking real-life 9/11 accounts, and I hope through him I have honored all those heroes.