The race for the lost keystone - Val Rutt

Kate and Phil Reynolds think they belong to an ordinary family. That is until a larger-than-life old lady turns up on a Harley Davidson with her golden retreiver Fearless in the sidecar, and introduces herself as their Great Aunt Elizabeth. And that is until they discover that their own cat, Barking, can talk, and that their legacy is ownership of some unique stones that have very special properties but come with a whole heap of reponsibility. And finally they find out that they are pitted against Lorabeth Lampton, an evil villainess of Cruella De Vil proportions, who is causing natural disasters on a worldwide scale in her quest for eternal youth. Kate and Phil Reynolds' lives are about to be irreversibly turned upside down...