In twelfth-century London, Magdalene la Bâtarde is the madam of the Old Priory Guesthouse in Southwark. She is not in the least bit sorry to learn that Bertrild, the unpleasant wife of Master Mainard, is dead. Bertrild was insulting to most people. She made threats, using terrible revelations as a weapon against those who would not bow down to her demanding ways.
However, when it seems that Mainard will be charged with Bertrild's murder because no one accepts the oath of a whore that he is innocent, Magdalene, with her handsome friend, Sir Bellamy, decides to investigate.