All my life, we’ve been talking about World War III,” Ken Follett says. He’s Zooming from his cosy study in Hertfordshire, England. That a third global war would be the subject of his forthcoming novel, Never (Viking, Nov.), seemed almost inevitable to the bestselling author.

“I was born in 1949, around the time the Soviets exploded their first nuclear device,” Follett says. “So the danger of a war that could destroy human civilization has really been with us since I was born. Never must have come from a deep-seated anxiety that seeped into me from a very young age.”

Never is a departure and a return for the megaselling author (Viking says Follett’s books have sold more than 178 million copies worldwide), marking a return to his roots in espionage thrillers. Though he became a household name for his 1989 doorstopper The Pillars of the Earth, about the building of a cathedral in 12th-century England, and further burnished his reputation as a master of historical fiction with the sweeping Century trilogy, which follows five families from WWI into the 1980s, Follett’s tales of spycraft first put him on the literary map.

In the early 1970s, Follett launched his writing career as a reporter, first at his local newspaper, the South Wales Echo, later at London’s Evening News. Then he moved into book publishing, taking a job at Everest Books, a small press in London. He began writing fiction in his free time and published five spy thrillers in the mid 1970s before finding success with 1978’s The Eye of the Needle. The novel sold more than 10 million copies, according to Viking.

By then, Follett says, he’d figured out the secret sauce. “It was an early decision of mine to look for real-life situations where the work of a spy could change the course of history,” he recalls. “I’d ask, ‘What if there had been a spy who had better intelligence on the other side of this conflict? What if we knew there was that spy and we were trying to catch him?’ ” He says it’s a winning formula that, “like the 12-bar blues, no matter how many times you do it, it always works.”

Follett says that while doing research for his thrillers, he hit upon the idea for The Pillars of the Earth. “I began to find compelling stories that existed on a broader canvas. That was something I had to learn how to pull off, because a tightly focused thriller is a heck of a lot easier to write than a historical novel with five POV characters and a wide geographical acreage. The Pillars of the Earth was a very difficult novel—it was like learning to be a writer again.”

The work paid off. Pillars has sold some 26 million copies worldwide, per Viking, and been adapted into both a TV miniseries and a computer game.

Never is an 800-page epic thriller spanning multiple continents with multiple story lines. Its interconnected plots follow characters who include a CIA operative facing the Islamic State in the Greater Sahara in Chad; a young widow escaping human trafficking in Libya; a senior Chinese government official butting horns with the old Communist guard in Beijing; and the president of the United States, a moderate conservative who is embroiled in a heated primary with a Trump-ish challenger. It maps current geopolitical conflicts—such as territorial disputes in the South China Sea—and the way such situations can force the hands of global superpowers. It’s also a cautionary tale that leads to nuclear war.

How these conflicts play out in embassies and governments around the world feels deeply authentic, largely thanks to Follett’s own peripheral experiences in politics. He notes that his wife was a member of Parliament for 13 years, “so for 13 years, half of our friends were running the country. Every now and then, we’d be sitting in a restaurant and one of them would say, ‘What are you going to do about so-and-so?’ The next day they’d go into Whitehall, talk to civil servants, and ratify the decision that had been made in that quick interchange at dinner. The way that kind of thing plays is very familiar to me.”

Never gives the sense that its author might be a little less than hopeful about the future of humanity. Is he?

“By nature, I am an optimist,” Follett says. “If I’m ever playing a game of chance, I always think I’m going to roll high dice, and no amount of experience to the contrary will change that. Most of my life I have felt that I knew the answers to political problems, but I have never felt as bewildered as I do today. So, yes, I think the world is in a dangerous place, and no, I don’t know what we can do about it.”

Throughout the novel, Follett weaves in threads of intergenerational angst between President Pauline Green and her idealistic teenage daughter, as they butt heads over political issues. “It comes from my own experience as a grandparent whose grandkids treat him with a kindly tolerance, as somebody who’s well-meaning but clearly out of date,” he says. “It’s all part of making Pauline’s story dramatic in a very human way. When you write a very powerful person, you’ve also got to make them vulnerable. A story that was just about the global crisis would have been a lot less satisfying.”

One of the North African story lines follows Kiah, a young widow who will do anything to escape poverty and build a better life in France for her two-year-old son. Again, Follett mined his own experiences of parenthood to offer a moving portrayal of a vulnerable young family. “Our feelings as parents toward our children are universal,” he says. “When I’m writing a story that takes place a thousand years ago, most of the tangible things about life are different, but the fundamental emotions are the same. People are still worrying about love and sex and family and money and work and violence and war. So, while I couldn’t possibly imagine what it’s like to be an illegal migrant traveling across the Sahara on a bus with hostile jihadis, I can imagine what it’s like to be a parent worried about their child. I can imagine what it’s like to be somebody who’s broke and desperate and has to take a risk.”

Follett himself has gone from being a young journalist writing novels in his free time to being an author with millions of readers. So how does he feel when he looks back on his own career?

“The thing I’m most proud of is being able to do it for so long,” he says. “It takes a lot of determination to say: ‘No, I’m not going to publish a second-rate book, even though the publishers would take it and sell it and we’d make money.’ It can’t just be good. If I want my book to be read by 10 million people—which is about the norm for me now—it’s got to be terrific.”

Laura Steven is a journalist and author from Northern England. Her journalism has been featured in Buzzfeed, the Guardian, and The I.