Whisking her staid guardian Brinnie off to Illyriaa tiny kingdom on the Adriaticto investigate one of her late father's theories, she involves them both in a search for treasure, an attempted revolution and a conspiracy to murder Illyria's King Osman. With the help of the rebel leader Vartan and in spite of Brinnie's habit of trusting the villains, Vesper solves an ancient puzzle and shows rebels and proud King how to make peace. A touch of romance adds the finishing touch.