Cressida Cowell may be her own tough act to follow but she’s about to give it a go. The author and illustrator behind the How to Train Your Dragon franchise–including a dozen books, three films, and spinoffs produced for both the Cartoon Network and Netflix–will launch a new middle-grade series this fall. The cover of book one in The Wizards of Once series is revealed here for the first time.

“When I wrote the first Dragon book, absolutely nobody was paying any attention. I was completely unknown,” Cowell said in a telephone interview from her London home. “Now after the big Hollywood movies, and the television show, and everything else, I suppose there is a bit more pressure, but it’s lovely that people are going to notice. You wouldn’t want it the other way around.”

The new series was acquired by Megan Tingley, executive v-p and publisher of Little, Brown Books for Young Readers in the U.S. and Anne McNeil, senior publisher of Hodder Children’s Books in the U.K. The deal for the series was brokered by Cowell’s agent, Caroline Walsh of David Higham Associates. All three women have been with Cowell “from the start,” she said. “It’s nice because you have the sense of building something with people. Even when things are very successful, they don’t happen overnight.”

Cressida spent 15 years writing the Dragon series, which was inspired by Viking-era Scotland. The new series will pedal even further back in time to the British Isles during the Bronze Age. “I like to root the stories in real history because it makes the fantasy much richer and it gives me ideas for plots,” Cowell said. “When I discovered through research that the Vikings were skiers, it gave me an idea for a whole novel.”

The main character in Once, Xar, lives in a society that values magic above all else–but Xar’s magic isn’t working. His life alters after a chance encounter with Wish, a warrior with the opposite problem. She has magic but lives among people who believe spells and sorcery are evil. “Their bond is that they’re both outcasts,” Cowell said.

The initial plan is for three books, but that was the initial plan for Dragon, too. “It’s a big world, quite a rich world, so I have an overriding story arc, like I did with Dragon, but so much about my writing process is driven by getting kids to want to read,” Cowell said. “With all the competition from films and the telly, it’s sometimes such an effort to get them into books. So when they do get into something, you want to give them more, because books are a medium I truly believe we cannot afford to lose. For me, it’s a bit of a mission.”

Cowell, who studied literature at Oxford University before attending art school, writes and illustrates her books in a “shed at the bottom of the garden,” using both strands of her education, almost equally. “Am I a writer first? I suppose I am but I see things quite visually,” she said. “It’s also a bit of an acting performance because I’ll talk it aloud in the shed while I’m writing.”

A workspace away from her house is a necessity since she began writing in earnest years ago, just as the first of her three children was born. “Really, my entire career has taken place with little children around, an atmosphere of lovely chaos,” she said. “How to Train Your Dragon was very much inspired by having just had a baby. It could have been titled How to Train Your Baby, or How to Be a Parent.”

That baby, now 18, left home just as Cowell was finishing the Dragon series and starting work on Once. “It was a hugely emotional time for me,” she said. Cowell’s husband, Simon (“not THAT Simon Cowell,” she writes on her website) quit his own job four years ago to give Cressida more time to devote to the demands of creating and managing a literary empire. Their youngest child is now 13, meaning Cowell is finally free to do more traveling in support of the new series. Little, Brown will bring her to the U.S. for a two-week tour in October.

Cowell realizes that no matter how well received Once is, she will answer a lot of questions about Dragon. That is completely fine with her. “I get tons of fan mail, tons,” she said. “But I would never complain about that. How lucky it is that you’ve written something that has resonated with so many?”