When Nick and Katie read in the paper that some friends of theirs have inherited a mysterious, cursed ruby, they're eager to hear all about it. But before they can arrange to visit them, Sophie and David are kidnapped. Nick and Katie resolve to tackle another riddle and set out to look for their friends. A hastily scribbled note and a mis-heard place name are the only clues they have. The trail takes them to unexpected places and some very strange discoveries.