Jonathan is hugely excited. He's about to go on a class trip to an old castle. And the best part: his glowing green friend Cara, the ghost girl, is coming too! What with their disorganised teacher Mr Bierbacher and Cara's ghost pranks, it's going to be great fun. But it soon becomes clear that the castle is haunted! What Jonathan can't grasp is that the person who's most afraid is Cara! What kind of ghoulish spectre can make even a ghost girl scared?