Star Riders of Ren (Singreale Chronicles, Book 2)

In the land of Ren, Graygill heroes Raccoman and Velissa meet the mystical King Ren, whose knights are locked in a war of betrayal. Many of the knights have left the palace, taking on new and hideous forms, and have challenged Ren's right to rule. Complications arise when the King disappears and his nephew usurps the throne.