Margaret is presented to George Barr McCutcheon, who relates for her especial benefit some of the incidents he has happened across, which have provided material for his famous romances. Captain James Curtin is a United States cavalry officer stationed in New York City. He falls in love with a beautiful girl, who visits the grounds at headquarters, and a later meeting on Fifth Avenue convinces him that his feeling is reciprocated. They are prevented from coming to an understanding, however, by the interference of an elderly man, apparently the girl's father, who hurries her away. The captain's only clue is a small coin with which the supposed father has tipped a bell-boy. Curtin learns that it was minted in one of the Balkan states. He goes abroad and finds the kingdom whence the money came. There he learns that the girl is Princess Olga and the elderly man, Prime Minister to the King, her father. The Prime Minister is at the head of a conspiracy to usurp the throne. Meanwhile, the Princess and the Prime Minister have returned from the United States and the conspirators, fearing the young American's influence, decide to act at once. Captain Curtin overhears their plan, averts the national calamity, saves the reigning family, and wins the Princess for his wife.