A young girl, Rella Deveraux-PenSword, is called to protect and defend Hleo: an enchanted refuge for the children of Earth One. Rella must stop a plague of Shadowsplitters, the miscreations of the plagiarist Archimago, from destroying The Wondercurrent: a source of life and hope for all the children under Hleo's protection.

Rella's parents, Winter and Julian, are part of a secret alliance of Storykeepers. First, her mother disappears. Then, a few years later, when her father goes missing, Rella is forced to flee her home in the rural village of Ensea (Earth One). In flight, she is mysteriously transported (beneath her grandmother's green quilt) to the magical world of Hleo. There she embarks on a quest and teams up with a fellowship of four other children: Eurie, Quinn, Scarlett, and The Wooden Boy Sebastian.

Will Rella be able to destroy the plague and help save the enchanted refuge of Hleo? Will she find out the truth about her parents? Will the guardians and the fellowship of children be able to save The Wondercurrent … and The Red Notebooks?