The Dragon and the Stone (The Dream Keeper Saga Book 1‪)‬

Even though she's only 12 years old, Lily McKinley already feels the weight of the world's brokenness. She's seen it in her mother's exhaustion, her grandmother's illness, and the cruelty of Adam, the bully at her school. But most tragically, she experienced it two months ago when her father died in a terrible accident. 
As an artistic daydreamer, Lily has a brilliant imagination to help her cope, but that imagination often gets her into trouble. One day, it transports her to a fantasy world called the Somnium Realm, where her father's secret history embroils her in an epic quest. With the help of a dragon guide named Cedric, Lily battles evil shrouds, harpies, and other creatures to find her way through grief, rescue the world from evil, and discover the power of redemption. 
This thrilling novel by Kathryn Butler mixes fantasy with Christian themes, taking middle school listeners on a quest through castles, forests, and caverns to help a young girl find hope and usher in restoration.