Conquest of Greystone Valley

Sarah is a teenage wizard, and she learned her magic from her mom. But where did her mom learn it?
When her best friend gets kidnapped by sword-wielding monsters, Sarah finds herself confronting a past she's been made to forget. She must journey to the magical world-between-worlds known as Greystone Valley, with many deadly dangers of its own.
Joined by friends both new and old, Sarah faces an enemy that magic alone can't defeat. Will she be able to save her friend, or is she destined to be forgotten, too?