On social media there's this thing where on many occasions, there's a single proscribed way of acting. Like if somebody dies, everyone has to say "R.I.P.! R.I.P.!" Basically they're saying, "Don't hurt me, I'm a good person."

My ideal world was the early days of Twitter, where everyone was curious about each other and everyone saw it as kind of a window into people's lives where we could be compassionate and curious and empathetic and we could tell each other secrets.

There is no evidence that we've been placed on this planet to be especially happy or especially normal. And in fact our unhappiness and our strangeness, our anxieties and compulsions, those least fashionable aspects of our personalities, are quite often what lead us to do rather interesting things.

Guy Savelli's role in the War on Terror began when half-a-dozen strangers, within days of one another, contacted him via e-mail and telephone in the winter of 2003. They asked him if he had the power to psychically kill goats. Guy was bewildered. He did not go around publicizing this. Who were these men? How did they know about the goats? He feigned a casual tone of voice and said, 'Sure I can.'Then he phoned Special Forces.

We have to understand how the extremists got the way they are. Without that kind of understanding, we'd never really get to know them. I put in nothing about their childhoods. But what I have put in is stuff about the weird symbiotic relationship between us and them.

Obviously, I like to write stories that are page-turners. But I always try my very, very hardest to be as factually true as possible.

Trying to solve the mystery is what I enjoy most about writing.