You’d have to inoculate your entire population—and maybe that wouldn’t work by the time the pathogen circulated back around to you.

The Soviet Union was very much a castle on the hill. The wall hadn’t come down yet when they were building the plague super-weapon. And the Russians didn’t exactly fly to Paris for the weekend, so maybe there was this idea of, “We’ll inoculate everybody with a plague vaccine and the West can all die off and we’ll march in later and take over.”

You also point out that plague was perhaps the first bioweapon—when a 14th-century army led by a descendant of Genghis Khan threw plague-ridden corpses over the walls of the Republic of Genoa.

Yeah, it has had a long history, and it’s something pandemic planners and Pentagon war gamers consider a very serious threat. Pneumonic plague is airborne, with a 100 percent kill rate.

There aren’t many things with that kill rate.

Just rabies virus and plague. So, working to erase the existing medical countermeasure of antibiotics from a disease with a 100 percent case fatality rate [as the Soviets did]—that is dark.

You even made your plague a chimera—two pathogens in one!

Only because the Soviet scientists did it in the 1980s.

You think such demonic things still exist in Russia?

I can’t imagine that they wouldn’t. The way the State Department describes it, the illegal Soviet-era program was absorbed into the new Russian program. Which is deeply disturbing.

So, what’s next on your agenda? More terrifying scenarios?

[Laughs.] I write in my acknowledgements that the point is not panic. The point is pressure. On book tour, I’ve had so many people [who’d heard my book was terrifying] say, “I read it and I actually feel less terrified.”

You begin to realize there are existential fears that are based on hypothetical worry, and then there are real threats that you should be aware of. I would hope that my books would add to that part of the conversation.