Some double-crossing wizards have locked up Measle's mum and dad. So now it's just Measle, his baby sister, and his little dog Tinker-and they're up against . . . well, just about everybody. And when everybody's after you, you need somewhere to hide. Caltrop Castle may look safe enough with its huge bolted doors to keep the lurking horrors out. But what if the lurking horrors are already inside? Poor Measle, even the castle itself is out to get him . . . The third instalment of the fantastic Measle Stubbs Adventures.