It follows the adventures of Princess Arianna of Balinor and her unicorn, Sunchaser as they restore the Royal Scepter and rally the kingdom to defeat an evil entity known as Entia the Shifter.
Ari Langley is a thirteen-year-old girl recovering in the hospital and suffers from memory loss after a mysterious accident that has left her legs severely scarred.
Her only prominent and familiar memory is a strong connection to a Chase, one of the horses at the Glacier River Farm where Ari lives with her foster parents, Ann and Frank.
However, Ann and Frank realize they cannot afford Ari's medical bills and decide to lease Chase for riding lessons to the obnoxious and spoiled Lori Carmichael.
Though its powers are unknown to them, Ari, Chase, Linc and Lori journey through the Valley of Fear and across the Fiery Field to Entia the Shifter's castle.
As the herd's colors and spirits are fading, and Naytin causes destruction to the land in search of the missing jewel, Ari and Chase quest to reclaim the Star.
Before she can lead her people into battle, Arianna must forge alliances with the Great Houses, diplomatically solve disputes, and accept the loss of an old friend.