Philip Reeve returns to the world of Mortal Engines in YA steampunk novel Thunder City, an all-new adventure set between the Fever Crumb prequel series and the original saga. When the city of Thorbury is taken over by ambitious Gabriel Strega, Miss Lavinia Torpenhow embarks on a quest to save her home. To help her rescue the son of Thorbury’s late mayor from protective custody in Paris, she recruits Tamzin Pook, a gladiatorial champion from the raft town of Margate. With both Strega’s agents and Tamzin’s former captor in hot pursuit, the would-be heroes travel by land, sea, and air to fulfill their quest. In a conversation with PW, Reeve talked about the mechanics of reinvigorating a long-running series and how he generates new ideas.

In a blog post discussing Thunder City, you said, “I thought if I wrote another Mortal Engines story I was likely to end up just repeating myself.” Why did you decide to return to the series now?

I think when you’ve created a world like this, it’s sort of always there in the back of your mind; it doesn’t really go away, even though you thought you’d finished the story. I’ve always had an itch to go back and see what was going on in other bits. I resisted it for a long time, and then I thought, “I could just use that world as a backdrop for a new story, rather than worrying about the stories that already happened.” That struck me as quite an interesting idea. I set Thunder City 100 years before Mortal Engines so that it can’t involve any of the same people and gave myself the challenge of not revisiting any of the places from the original series.

Inevitably, there are echoes of similar characters, but the hope is always that, if different things happen to them and they have different experiences, they’ll develop in different ways.

I think when you’ve created a world like this, it’s sort of always there in the back of your mind.

What are some things that fans of the Mortal Engines and Fever Crumb books can expect to find in Thunder City?

It sort of uses the Fever Crumb books as history—they are the history of what has happened to this world and how it’s developed, after all. People who read Fever Crumb will recognize that, although it’s not important for understanding Thunder City; I very much set out to make this work for people who haven’t read any of the other books.

Even though it’s set a century before Mortal Engines, the time that Thunder City takes place in hasn’t altered the world very much. It’s slightly more genteel than the original books. It’s more low stakes. There’s still adventure, but it’s only the fate of one small city at stake; there aren’t any great world-shattering events happening. Writing it felt more like writing a thriller or The Three Musketeers. Because I’ve been living with this world for so long and it feels completely real to me, creating Thunder City felt like writing a swashbuckling historical adventure.

In thinking of Thunder City and the Fever Crumb series as historical adventures in the Mortal Engines world, how did the development of previous books play into writing Thunder City?

Fever Crumb feels very separate to me because the original four Mortal Engines books are set in this world of roving, rampaging motorized cities. With Fever Crumb, I went back about 500 years and tried to decide who was the first person to think this would be a good idea. Which idiot thought of this? How did it begin? Because in Fever Crumb, there are no motorized cities yet, so it was a very different environment.

Also, I think motorized cities are more fun than the unmotorized variety. So that’s why I went for something much later in the period with Thunder City. I wanted to get back to the original Mortal Engines vibe.

Have you considered what things you might have changed or done differently in previous books knowing what you know now about the world you created?

It kind of is what it is. If I want to do something different, I create a different world. I’ve written other books, like the Rail Head trilogy, that were set in entirely different imagined worlds. Mortal Engines has its own crazy little reality, so it seems pointless to worry too much if things aren’t right. When I was writing the first book, for some reason or other, I got rid of America. I thought it would be too much of a bother to have Chicago and New York rolling around. But the thing is, they will have been bigger and cooler than all the European traction cities, and I didn’t want that, so I destroyed you. I believe I said that nobody ever goes to America. As I keep writing, it has struck me that this seems to be more and more unlikely. There must be something going on there, and it would be very nice to find out what it is, but I’ve never actually managed to get a character across the ocean yet to find out.

I’m hoping, if enough people are interested, that I’m able to keep going and do sequels to Thunder City—maybe Tamzin Pook and her friends end up exploring the mysteries of the dead continent.

Is there a correct order in which to read the Mortal Engines books?

I think the one to start with is Mortal Engines, because that was the first published book I ever wrote, so I would hope that if you start with that, then the writing will improve as you go on. I think it also has a kind of energy that you can probably only get from someone’s first novel. For all its flaws, I think it has this mad punk energy to it, which is what appeals to people. Then if you carry on to Predator’s Gold, Infernal Devices, and A Darkling Plain, you’ll get to learn more about the stories of those characters over something like a 20-year period. And if you enjoyed the experience, you could go back and find out where it all came from by reading Fever Crumb.

But Thunder City is a sort of wild card. It fits in anywhere you want it to. You could start with it, or you can chuck it in the middle of the others. It’s sort of disconnected in that sense; it’s free-floating within the world of Mortal Engines.

You’re also an illustrator and have collaborated on two musical comedies—The Ministry of Biscuits and Lord God—with playwright and composer Brian Mitchell. How do these other creative endeavors inform your career writing for children and vice versa?

I’m not sure they do. When people hear I’ve done illustration, they always assume that that’s where my work in children’s books comes from, and that I must sit there drawing pictures and writing stories around them. But it doesn’t really work out that way. I very seldom draw these days.

Writing the musicals with Brian was great, but I’ve also taken to making little movies. I made a film called Gwenevere. It’s an Arthurian romance that I shot with my wife and posted on YouTube. We hired some actors and filmed it in Dartmoor, the area of countryside where we live. It was incredibly exciting and, in a way, it inspired Thunder City. The actress we hired to play Gwenevere [Laura Frances Martin] has since become a friend, and she’d be very right to play Miss Lavinia Torpenhow.

Overall, it’s all about finding different ways to tell stories. If you’re telling a story in an extremely low-budget film, you have to think on your feet and come up with ideas and shortcuts, and that all plays into writing. It’s like exercise or R&D: it keeps you limber and you come up with new ideas that way.

Speaking of new ideas, what else are you working on?

I worked on my second film, which is a Western. The landscape around us is very good for Arthurian legends, because it’s all misty rocks and tangled woods and stuff, but we’ve also got quite a lot of high, open country and pine woods, so I figured we could do a Western. That was shot over the summer, and I’m editing it now. It’s called Prairie Rascals.

I’ve also worked a lot with an illustrator friend, Sarah McIntyre, on a series called Adventuremice about a band of tiny mice having adventures in ships and things. Those are terrific fun. They’re a completely different type of book to Mortal Engines; they’re aimed at five-, six-, seven-year-olds. Sarah is one of the reasons I don’t illustrate anymore—she is so much better at it. So we do the roughs for the books together, and then she does the final artwork, and it’s magnificent. We’re doing two of those a year at the moment, so I’m busy writing the next one, and I’m coming up with a sequel for Thunder City. And after that, I’m not entirely sure. I’ll have to wait and see if inspiration strikes.

Thunder City by Philip Reeve. Scholastic Press, $19.99 Nov. 12 ISBN 978-1-5461-3823-5