Five years after fleeing the French Revolution, Anne-Marie Dupont now lives as an English commoner alongside her drunken father, Baron Pierre Dupont. While her father detests their newly unadorned life, Anne-Marie is glad to be rid of her once noble traditions; namely, the burden of childbearing. However, whilst working in their shop as a translator, a royal courier arrives bearing an invitation to Windsor Castle from the King. Despite Anne-Marie's wariness, her father happily accepts, hoping to return them to their once noble life.
Upon arriving at the royal estate, the Baron is ushered away to a private meeting with the King, where he signs Anne-Marie into service as the Queen's maid-of-honor. She then meets with the Queen, who informs Anne-Marie of her true role in the royal court: she is to become the King's mistress, with the sole purpose of birthing a male heir. Horrified at the prospect, Anne-Marie initially refuses, but after the Queen threatens to send her and her father back to France to face certain death, she has no choice but to accept.
As her predicament steadily worsens, Anne-Marie becomes more and more desperate to do whatever necessary to escape her situation. She soon finds that the castle holds a grisly secret, one that reveals the truth about her role and the inevitable fate that may eventually befall her. In order to escape, Anne-Marie must take increasingly extreme measures in the face of the ever-present Crown, risking not only her life but that of her unborn child as she delves deeper and deeper into the depths of madness.