Iron Butterflies is the story of Amelia, an American woman who goes to Germany to clear her grandmother's name. Her grandmother (deceased) had married a foreign prince who had to return to his country (a principality of Germany) and marry a princess. In America, the second marriage was not recognized; in Germany, the first was not recognized. Now the prince is dying and sends for Amelia.
However, Amelia discovers that there is a delicate balance of power in the principality, and that she has become a powerless piece in a game she does not understand. She undergoes a secret midnight visit aided by a clever, loyal maidservant, a mock marriage, a removal to the countryside, a removal to an ancient stone prison with secret passageways, and the ministrations of a crazed worshipper of an old evil. Although the story is dark, it all turns out okay -- quite happily, in fact: Ameila falls in love with her protector in their escape.