The Mossheart's Promise by Rebecca Mix

Skip to product information
1 of 1

Click to look inside

The Mossheart's Promise by Rebecca Mix

Regular price
Checking stock...
Regular price
Checking stock...
World of Books

At World of Books, you’ll find millions of preloved reads at great prices, from bestsellers to hidden gems. Every book you buy saves money and helps reduce waste, so you can read more for less while giving stories a second life.

The feel-good place to buy books
  • Free US shipping over $15
  • Buying preloved emits 41% less CO2 than new
  • Millions of affordable books
  • Give your books a new home - sell them back to us!

The Mossheart's Promise by Rebecca Mix

From New York Times bestselling YA author Rebecca Mix comes the first book in a breathtaking middle grade fantasy duology about a young fairy who has always lived in her heroic grandmother's shadow but now must step up and embark on a quest to save her mother from the ever-creeping mold overtaking their world.

The mold takes all.

Twelve-year-old fairy Canary Mossheart knows this better than most. A few years ago, the mold took her papa, and even her famous, former-chosen-one Gran never found a cure. So when Ary's beloved mama falls ill, Ary decides it's taken enough. Armed with only a bucket and a prayer, she sneaks out to find a magical, underground lake whose healing waters are straight out of Gran's adventures. 

But when Ary gets there, the lake's bone dry, and instead of healing waters, she finds a terrifying secret: Her entire world is actually trapped inside a giant terrarium--one they were meant to leave centuries ago. Worse, Gran knew and hid the truth, dooming Ary and her generation to a dying, rotting world.

Now, allied with only her doomsday-obsessed frenemy, a timid pill bug, and a particularly grumpy newt, Ary has one week to unravel the clues and find a way out of the terrarium--or they'll be trapped for good. 

Perfect for readers who loved Brandon Mull's Fablehaven, The City of Ember by Jeanne DuPrau, and Endling: The Last by Katherine Applegate.


  • A Breathtaking Eco-Fantasy: Discover a world trapped inside a giant terrarium, where a creeping mold is destroying everything and the only hope lies in escaping a home that's turning into a tomb.
  • A Desperate Race Against Time: With her mother growing sicker and only one week to find an exit, Ary must unravel clues left by the one person she can no longer trust: her own grandmother.
  • A Magical Coming of Age Story: From a timid girl stealing mushrooms to a brave adventurer on a mission, Ary must find her own courage to save everyone she loves.
  • Found Family: Joined by her doomsday-obsessed frenemy Owl and a shy-but-sturdy pill bug named Shrimp, Ary learns that the most unexpected allies can become the family you need most.
SKU Unavailable
ISBN 13 9780063254053
ISBN 10 0063254050
Title The Mossheart's Promise
Author Rebecca Mix
Condition Unavailable
Binding Type Hardback
Publisher HarperCollins Publishers Inc
Year published 2023-09-05
Number of pages 432
Cover note Book picture is for illustrative purposes only, actual binding, cover or edition may vary.