As the city of Florence basks in afternoon sunlight, pleasurable anticipation stirs in the heart of beautiful Marianne d'Asselnat, Princess San'Anna. The trials and uncertainties of her eventual past life seem almost over, for she is soon to rejoin her beloved sea rover Jason Beaufort and enjoy with him a peaceful future in America. So she is not particularly dismayed when called upon to render a last vital service to her master, the Emperor Napoleon, whom once she had known as lover and still called friend. But, abruptly, an ominous shadow appears in her future, cast by the dark influence of her unseen husband, the mysterious masked Prince Corrado. The tricks of fate then force her to embark on a perilous odyssey which carries her from luxurious Venice, through Greek islands smoldering with revolt, to the court of the legendary Sultans of the Ottoman Empire.