A true crisis. Class 3 outbreaks, more than any other, demonstrate the clear threat posed by the living dead. Zombies will number in the thousands, encompassing an area of several hundred miles.

But there were alternative media outlets. Oh sure, and you know who listens to them? Pansy, overeducated know-it-alls, and you know who listens to them? Nobody! Who's going to care about some PBS-NPR fringe minority that's out of touch with the mainstream? The more those elitist eggheads shouted "The Dead Are Walking," the more most real Americans tuned them out.

We live in such a service-based, globalised economy where very few people actually make anything and the people who do make stuff... it's all part of a massive global supply chain. So what if all those chains were suddenly cut, how would you make something? How would you keep people alive? And that was something I wanted to explore.

They were viewed very much like castles, I suppose: as crumbling, obsolete relics, with no real modern function other than as tourist attractions. But when the skies darkened and the nation called, both reawoke to the meaning of their existence. One shielded our bodies, the other, our souls.

That's the thing about zombies. They don't adapt and they don't think. Literally, you could have a zombie on one side of a chain link fence and you could be on the other side and they could be trying to get to you and six feet down could be an open door and they will not go through that door in the fence. That's why they're so scary.

I think 'G.I. Joe' is a perfect example of how I'm the world's worst businessman. If I were smart, I'd be writing 'World War Z Part 12', but I have to go where the muse leads, and I've always been a huge 'G.I. Joe' fan. I always wanted to know more about these characters, these little plastic figures I played with as a kid.

I think the general anxiety of the 1960s - '70s spawned our interest in the living dead. When people worry about the end of their world, they need a safe vessel for all their fears. Zombies provide that vessel because they're 'safe.