The Flight Of the Mytar — Robert Cole

Chris, Susie and Joe are transported back to Earth to find the remaining Mytar. To their horror, they discover that two of the three Mytar were the bullies that had tormented them at school. With the agents of Zelnoff closing in, they are forced to transport them back to Cathora against their will. Once there, these two new Mytar refuse to help and reignite old hatreds and conflicts. Hunted by the Nethral and the Taal, the Mytar children are chased relentlessly through the underworld. It becomes a race to find the sixth Mytar and develop their powers before they are captured and killed by Zelnoff's forces.