The Illyrian Adventure is the first of a series of novels featuring Vesper Holly.

Subsequent titles are The El Dorado Adventure (1987), which takes Vesper to Central America; The Drackenberg Adventure (1988), which finds her attending a diamond jubilee celebration for the Grand Duchess of Drackenberg;The Jedera Adventure (1989), in which she returns an ancient book, borrowed by her father, to a library in North Africa; and The Philadelphia Adventure (1990), in which the now twenty-year-old Vesper meets again with Dr. Helvetius of Illyria.