Graustark needs thirty million dollars to satisfy a Russian loan. The Prince of Dawsbergen, ruler of the adjoining principality, will advance the money if the young Prince of Graustark marries his daughter. Prince Robin, however, inherits an independent spirit, his father having been an American. He refuses absolutely to marry a Princess whom he has never seen. His councilors plead in vain. With the ruin of his country imminent, the boy ruler hastily sails for America to negotiate the loan, hoping at the same time to meet the girl of his dreams. The money is readily advanced by William W. Blithers, a self-made millionaire anxious to have his daughter marry into royalty. The daughter, however, avoids the Prince and he does not see her. He rescues a girl from drowning and falls in love with her. He believes her to be Blithers' daughter, but she does not reveal her identity.

Denton, an anthropologist of note, meets by accident a new neighbor, an attractive girl, whose father insists upon her marriage to a man whom he favors because of his wealth. Denton and the girl are mutually attracted and to Denton comes a vague but haunting belief that they have met before. Worn out by overstudy, he becomes seriously ill with rain fever and the mind pictures he has of his fair neighbor fade into a vision of a prehistoric existence, where he wanders as a stone age savage, meets and loves the girl of his heart, who also lives in that strange world. There also is the conflict between wealth and poverty, the father's choice opposed to the daughter's. The prehistoric Denton finally wins out after struggling with a savage rival and wild beasts as well. Just so the modern Denton finally conquers over his modem rival.

A romance set in the court of Spain, in which Don John of Austria is in love with Dolores de Mendoza, daughter of the commander of the King's Guard.

While traveling by train from Denver to Washington, DC, wealthy young Grenfall Lorry meets a beautiful young girl. When they are accidentally left behind in a mining town, they race through the mountains and finally catch it. They travel to Washington and have a great time, but they soon part. They meet again later in the small European country of Graustark, where Grenfall and his friend Harry rescue her from kidnappers, and they then discover that she is actually the country's Princess Yetiva. She is engaged to Prinze Lorenz of Asphan in order to pay off Graustark's enormous debt from the war, but Lorenz is murdered and Grenfall is framed for the crime. Complications ensue.