The lllyrian Adventure is the first of a series of five books about the adventures of sixteen-year-old Vesper Holly.
It is a fast-paced, exciting story with a suspenseful plot and a delightfully enterprising protagonist. At the beginning of the novel, the recently orphaned Vesper persuades her guardian to join her in a dangerous mission in the tiny country of Illyria on the seacoast of the Adriatic. Her purpose is to redeem the reputation of her historian father, who in his work about Illyria referred to a "magical army" that no one believes could possible have existed. The lively characterization of Vesper enhances the engrossing plot, with its focus on an archaeological mystery.