The Darkstone makes the Red Witch the most powerful of mages but there is a terrible fallout from its use. A Blight spreads across mainland Briton, killing adults but leaving children to struggle to survive.

Bryan, leading a group of orphaned children, encounters Aina whose little boat can take them to temporary safety, but being involved with her is dangerous. She is on a mission to save their world, but the Red Witch will do anything to stop her. Aina, Bryan and Jimmy Chan travel to another world to find twin children with the power to destroy the Darkstone.

The children become involved with sets of rival magicians. An agent of the Red Witch is here also, scheming for control of the twins and accompanied by a terrible beetle-like creature whose nature hides a terrible secret. Despite the danger, Bryan and Aina persuade the twins to return to their world. Their final mission is a desperate attempt to penetrate Ynis Mawr and take on the Red Witch herself..