Purchases you make through our links may earn us and our publishing partners a commission. 

As a member of the bestselling girl group in history, Geri Halliwell-Horner has circumvented the globe and brandished her Union Jack minidress to millions of people.

But for the past seven years, she’s relished being ensconced in her writing shed in England, a dichotomous detour from the world of Ginger Spice and the Spice Girls.

This week, Horner released her debut young adult novel, “Rosie Frost and the Falcon Queen,” an engrossing adventure tale of the titular red-headed teen, newly orphaned and sent to mysterious Bloodstone Island where a school for exceptional students and endangered animals co-exist.

Rosie endures bullying and Hunger Games-esque challenges with her schoolmates while finding guidance from the wise ghost of Anne Boleyn and a particularly approachable wildcat.

Check out: USA TODAY's weekly Best-selling Booklist

The book – recommended for ages 10 and up – isn’t Halliwell-Horner’s first foray into literature. Along with her 1999 autobiography, “If Only,” the singer-author created the Ugenia Lavender series of children’s books starting in 2008.

Chatting from the back of a car on her way to Long Island as part of a weeklong book tour, Horner, 51, talks about the arrival of “Rosie Frost” – she just turned in a draft of the second volume and plans for a trilogy – what girl power means to her now and why reading has always been her “great escape.”

• “Rosie Frost & the Falcon Queen” at Amazon for $18
• “Rosie Frost & the Falcon Queen” at Bookshop.org for $17

More:Stevie Nicks enters the Barbie zeitgeist with her own doll: 'They helped her have my soul'

Question: Going from writing children’s books to young adult novels is a substantial leap. Why did you want to make it?

Geri Halliwell-Horner: I love writing. I studied English Lit before I got into music and I loved creating things. The power of words or whether we did movies or videos or the songwriting (in the Spice Girls), I felt confident. I wanted to age up (Ugenia Lavender) and I talked to Christopher Little (the literary agent who discovered J.K. Rowling) and he said, no, start over. I felt compelled that the world needs a new hero. My hope is that a 10-year-old or a 30-year-old or a 50-year-old can enjoy it; good stories defy age.

This is a substantial book at 451 pages. How challenging was it to develop?

The character was always there and I had written children’s books before but not big, chunky ones. It was a baptism of fire. I had other writers give me tips on what to do with structure. It was the hardest thing I’ve ever done mentally and emotionally. I originally wrote it in first person, present tense. But then I showed it to (acclaimed Scottish author) William Boyd, which was a bit like giving “Humpty Dumpty” to Beethoven, and he said, “Rewrite it in third person.”

Was there ever any doubt about making Rosie a “ginger”? 

Here’s the thing: When you write, you write about what you know, so you can’t help put a little bit of yourself in the character. I try to be authentic to the character as well and when you’re red, you‘re in your own lane. You can look back at lots of characters – Annie, Ariel – and reds, you have to find your own path. It felt authentic for it to be her (hair) color.

There is a very Meta line in the book when Rosie’s roommate, Bina, has her headphones on and says, “The ‘90s was the golden age of pop music.” Do you think people will get the reference?

I didn’t go too far to mentionthe Spice Girls, but (Bina) also mentions she loves divas. Bina is based on a girl I know who comes from a Muslim background and she loves wrestling and ‘90s music. Everything is cyclical.

The theme of girl power is strong throughout the book. How has that meaning evolved for you during the years?

I think it’s gotten deeper and wider in the sense like Disney goes to Pixar. It transcends into something. I’ve looked back on the past and it makes me think about, what does it mean? For me, girl power means equality for everyone, bypassing race, gender, whatever. It’s such a bigger concept and it’s important for girls and boys.

Queen Elizabeth I and Anne Boleyn factor heavily in the story. Have you seen the musical “Six”? 

I loved “Six,” but if I would add one thing (to the show), I would have made Anne Boleyn smart. I got advised by someone to not include her in the book because she’s too contentions and why? It made me lean into her more and discover this was a human being and a mother who left a 3-year-old after she was beheaded and who was smart and brilliant.

There is strong subplot about nature and conservation. Have those topics always interested you?

I’ve always loved animals. When I was little, I watched a movie and there were lions in this movie and it really made me think about the world we live in. The Bloodstone Island animals really are endangered – wildcats and Komodo dragons. I don’t have any of the answers, but it’s valuable to question things. I always try to hide vegetables in chocolate.

How has the U.S. book tour been going? Do you feel you’re getting people who want to come see you as an author rather than a Spice Girl?

The turnout has been amazing. A transition happens and it is my hope there is a switch. I feel like a mother bringing a person out into the world. You nurture it and write characters and do your best and here she is.

You are a very vivid writer. Did you read a lot growing up? 

I did, and I think it’s because I didn’t have a lot of money growing up and it was a good solution to get out in the world. I’d go to the library and get a book. When I was little, others would go on vacation and I’d sit in my garden and read. If I didn’t feel connected to something else, I could connect to characters in books. It was my great escape and a safe place.

• “Rosie Frost & the Falcon Queen” at Amazon for $18
• “Rosie Frost & the Falcon Queen” at Bookshop.org for $17

More:Tell us your favorite Olivia Rodrigo 'Guts' song and we'll tell you what book to read