In The Kingdom of Back, Marie Lu entwines well-researched fiction with fantasy, conjuring a captivating tale of young Wolfgang Amadeus Mozart and "the other Mozart." Historical details come alive in this fantasy-infused account of the extremely close relationship between the musical genius and his lesser-known sister, Maria Anna.

The story begins in 1759, when Maria Anna, called Nannerl by the family, is eight years old and Wolfgang only three. Their papa says Nannerl is a "miracle," and he brings Herr Schachtner, "the esteemed court trumpeter of Salzburg," home to hear her play the clavier. If she impresses, she will surely be invited to play for Herr Haydn of Austria, then on to the royal courts of Europe, thereby raising up the prospects of a family "forever on the edge of respectable." But when Wolferl innocently distracts the good Herr, Nannerl's opportunity is lost. That night, annoyed by her brother's interruption and desperate for the approval of her demanding father, Nannerl falls asleep yearning to be "worthy of praise, of being loved and remembered." For the first time, she dreams of the Kingdom of Back: a wild-looking boy walks in the surf of an ocean "lit by twin moons," and the air ripples with a "melody so perfect" Nannerl "aches to grasp it."

Time passes, and Nannerl overhears her parents speaking of a future for her defined by marriage and childbearing. She is haunted, knowing that soon, when she leaves her childhood behind, her father will stop teaching her. For now, though, Nannerl happily retreats to the haven of her clavier practice, and the menuetts she loves to play. Wolferl begs to learn the clavier, too, and Nannerl quickly understands that he has a "remarkable ear," perhaps even better than her own. After trying a few chords, her brother asks her to tell him a story, and the Kingdom of Back resurfaces. As Nannerl describes the landscape--a forest with trees that "stand upsidedown" and a shore with "sand as white as snow"--she transcribes a strange song that seems to spring note by note from this other world. Woferl plays the tune and does it so well that wonder and "a small twinge of something" (Envy? Fear?) begins to take root within Nannerl. Her old wish comes back to her: "Make them remember me."And she hears the "sweet and beautiful" voice of the wild boy: "I can help you, Nannerl, if you help me."

As Nannerl carries on with the fairy story, the siblings slowly fill in details of the fantastical kingdom. At times, it seems as if the magical place actually unfolds around them, replacing their neighborhood with the forest, and they even catch fleeting glimpses in the streets of Salzburg of the wild boy, a faery princeling named Hyacinth. Later that winter, when Woferl's musical gift becomes apparent and the family travels to Vienna for the children to play at the royal court, Hyacinth is also nearby. In return for promising to give Nannerl the recognition she craves, Hyacinth declares he needs her to help him reclaim his throne in Back. Though he warns her that "wishes have a habit of surprising their makers," Nannerl's ambition leads her to push away her unease. Fully aware that composing is "a man's realm," Nannerl cannot help writing down the "irresistibly coaxing song" Hyacinth conjures for her, thus agreeing to the bargain. Encouraged by Woferl, who promises to keep her secret, she continues to produce music originating in her visions and dreams of this other world. But her affection for Woferl is tried again and again as it becomes increasingly apparent that her younger brother will live the life she desires, even to the point of getting credit for work she herself has composed.

Nannerl Mozart was supremely talented in her own right, a young woman whose musical accomplishments were many and varied but whose dreams could only ever end in marriage. Readers are repeatedly teased by the possibilities of what might have been had Nannerl been born into another time, with far different expectations placed upon her. Lu's author's note at the conclusion points out how the fantastical Kingdom of Back was actually invented by the two siblings during their long carriage rides across Europe; their saga of music and magic is set "in a real land, full of real kings and castles and courts," but manifests also in "a dream of fog and stars, faery princelings and queens of the night." The author adds classic fairy tale elements and weaves the imaginary kingdom in and around the life of the Mozarts, increasing the tension of the story as the Kingdom of Back becomes more powerful and menacing. Torn between her deepest longing for immortality and her need to protect her beloved brother, Nannerl must decide for herself what her true legacy will be. --Lynn Becker

Marie Lu is the author of the #1 New York Times bestselling The Young Elites series, as well as the bestselling Legend series and the Warcross novels. She graduated from the University of Southern California and jumped into the video game industry as an artist. Now a full-time writer, she spends her spare time reading, drawing, playing games and getting stuck in traffic. She lives in Los Angeles with her illustrator/author husband, Primo Gallanosa, and their dogs.

What inspired you to write this story of a little-known sister to the great composer, Wolfgang Amadeus Mozart?

Since I was little, I'd always been fascinated by the story of Mozart and his prodigious childhood--but it took until 10 years ago for me to learn that he had a sister at all, let alone one arguably as talented as him at composition and performance. I learned about Nannerl Mozart from a biography about her brother and remember thinking, How, out of all the things out there about Wolfgang, had no one ever bothered to mention this genius young girl? So I did a deep dive into her life and learned that the two of them, as children, had actually toured Europe together to play for kings and queens. During their long carriage rides, they created for themselves a fantasy kingdom they called Back, which they used to pass the hours together. This fact seemed so magical to me that I knew immediately I wanted to write a story about it--and about Nannerl.

Can you talk about some of your influences in developing the fantastical Kingdom of Back?

I've always loved the magical and the strange, places that feel like a fever dream. The Dark Crystal, old faerie tales (the unfiltered kind), stories by Guillermo del Toro, Alice in Wonderland and elements from Peter Pan all influenced my world for this novel. I wanted the Kingdom of Back to be both beautiful and dark, a place that felt (in contrast to rigid 18th-century Europe) colorfully surreal, somewhere you'd want to visit but perhaps not to stay.

Front and center is the way Nannerl’s options are severely limited by the expectations of her father and the times. How did you reconcile the treatment of women in the 1700s with concerns your present-day readers might have? Do you think women are still constrained by society’s expectations?

This was a heavy question for me. The real Nannerl, obviously, never gets to break out from those limitations placed on her and, even though the Kingdom of Back is a fantastical version of history, I didn't think I could change her fate. How, then, could I end the story with any note of triumph for Nannerl? I tried to write it in a way that both showed how things used to be for women and how things can be different today. Of course women are still constrained by society--we see it in so many ways, every single day. The difference now, though, is that many of the barriers society erected to enforce gender roles are coming down. There is more access to information now, more women holding up other women, and as that dam falters, more women who get to make the important decisions that empower future generations of women. As much as I hope Nannerl's story can inspire young girls to pursue their dreams, the book is written more for everyone else in a girl's life, people with the power to clear away the roadblocks that hold girls back. We can't just leave girls to pound at glass ceilings alone. It is everyone's responsibility to shatter those ceilings for them.

The desire to make something wonderful that will live on beyond its creator--to leave one's "voice in the world"--is so important to Nannerl. What do you think motivates Woferl?

I think Woferl was motivated by the same call, and I truly think he learned it from Nannerl, whom he adored and idolized. Leaving one's voice in the world is, I think, important to most creators. Woferl, of course, was given the chance to fulfill that desire.

The relationship between Nannerl and Woferl is wonderfully defined. I can believe she loves him dearly, even as she is increasingly jealous of his opportunities. How did find your inspiration for their dynamic?

I've always been interested in playing with sibling dynamics in my stories--probably because I'm an only child! I don't feel like I missed out on anything, but I do find the relationship fascinating, in all its different iterations, and especially so with two siblings experiencing such an unusual childhood. A lot of the inspiration for Woferl and Nannerl's relationship came from their real history together, where letters and documents seem to show that they genuinely loved and were inspired by one another. I also always like listening to all sorts of stories from friends with siblings, everything from blaming each other for using Sharpies on the wall to creating make-believe worlds together. Those snuck in occasionally to my chapters, too!

What's coming next from Marie Lu?

I have a science fiction series opener called Skyhunter coming out in fall 2020! I can't say much about it yet, except that it's my longest book so far and has been a huge challenge to write, but I'm pretty excited to introduce readers to my new crew.

Is there anything else you would like to share with readers?

Only that I hope readers end the book not just interested in learning more about Nannerl, but all the other people that history left behind--women, people of color, LGBTQIA+ people. So many stories! We all seriously existed and did extraordinary things. --Lynn Becker