Charlie and his friends are back danger, and the balance of power between the Children of the Red King has never been more dangerous. Billy finally gets his longed-for parents, but he soon wishes he hadn't when the oaths he's forced to sign come flying through the air at him. Charlie is haunted by a ghostly horse, mad with rage over an ancient wrong that happened in the sparkling Castle of Mirrors. The castle was petrified from stone into glass by the sorcerer Yorath in a terrible fire. Charlie's good friend Olivia is haunted too - but no one knows her new secret. Even with the power of Tancred's storms and Lysander's ancestors, Charlie Bone is running short of allies - just when he needs them most.