The Secrets of Underhill

About the Book

An eleven-year-old apprentice fights to save an ancient grove of magical trees that hold the key to her community’s survival in this page-turning fantasy adventure. Perfect for middle grade fans of Kelly Barnhill and Jessica Townsend.

Nick Sixsmith has spent her whole life on the road. The daughter of a traveling arborist, she moves with her mother from town to town, caring for the ironwood groves the communities rely upon. When a dangerous blight takes hold of these magical trees, they must journey to the city of Mistwood—her mother’s hometown—for answers.

Nick can’t wait to explore the prosperous city of Mistwood and all it has to offer: bustling markets and workshops, neighborhoods built under a roaring waterfall, and the vast ancestral grove of ironwood trees. But dark secrets simmer beneath the surface as people start to disappear and tensions rise in the city.

As the mystery grows, Nick and her new friends from Mistwood must follow the trail where it leads them: underground, to a strange, enchanting world called Underhill. Only there, among the roots of the ancestral grove, will Nick find a way to save her new home and the ironwood trees.

This immersive fantasy adventure combines vivid world-building with timely themes of environmentalism, and young readers will be riveted until the final page.


The Secrets of Underhill is a gorgeously rendered story of strange magic, environmentalism, and what it means to care for the ones we love and the world we live in. This is the exact kind of book that would have hooked me as a young, reluctant reader. I adored every page.”—Rebecca Mix, New York Times best-selling author of the Mossheart’s Promise duology

“A transportive ecological fantasy as lush in its message as it is in its prose.”—Esme Symes-Smith, USA Today best-selling author of the Sir Callie series

“A wonderful, heartfelt adventure, The Secrets of Underhill celebrates friendship, curiosity, and finding magic in the world around you.”—Marieke Nijkamp, New York Times best-selling author

“Readers will immediately want to take root in this wonderfully crafted environmental adventure filled with whimsy, heart, and hope.”—Justine Pucella Winans, award-winning author of the Stonewall Honor Book The Otherwoods

“A journey to the heart of a spellbinding new world. The Secrets of Underhill is a dazzling, deeply rooted story about how vital it is to feed curiosity, tend to our communities, and nourish a lifelong love and respect for all living things.”—Nina Varela, author of Juniper Harvey and the Vanishing Kingdom

“Enthralling. Kali Wallace has created a lush world full of natural magic and wonder, and I loved getting to join Nick, Oliver, and Lizard as they fight to protect that world.”—Lin Thompson, author of The House That Whispers

About the Author

Kali Wallace

Kali Wallace is the author of books for children and adults, including City of Islands, Shallow Graves, and Salvation Day. She lives in Portland, Oregon.

Product Details

  • Hardcover ISBN: 9781683693888
  • e-Book ISBN: 9781683693895
  • Page Count: 320
  • Release Date: January 28, 2025