Wealthy heiress Diane Westfall, bored with her life, hops into a green van and sets out to seek adventure. She doesn't know that four men are pursuing her--her cousin Carl, who wants her inheritance; Baron Tregar of the small Balkan country of Houdania, who believes that Diane may be the rightful heir to the Houdanian throne; Prince Ronador, who also believes she may be the heir to the throne but wants to kill her so he can get control of it; and Philip Poynter, a young American friend of Baron Tregar's who has met and fallen in love with Diane, and sets out to protect her.