Set in the fictional European kingdom of Lutha, the protagonist is a young American named Barney Custer, of Beatrice, Nebraska, who is the son of an American farmer and a runaway Luthan princess, Victoria Rubinroth.
Barney meets and falls in love with Princess Emma Von Der Tann, Leopold's promised bride and then becomes intimately involved in Luthan affairs, working to help the king and ultimately allowing himself to be proclaimed as king while impersonating Leopold to prevent Prince Peter from seizing the throne.