Isabel, Lady Wilde, mistress of King Charles II, has made a good living disguised as fortune teller Mistress Ruby, counseling London's elite. But after the murder of one of her customers, business has taken a downturn, and Isabel is on the verge of accepting the king's offer to move into the palace. Isabel's plans are interrupted when a beggar girl named Susanna shows up at her home, claiming to be her niece. Isabel always believed that her older brother, Adam, died alone during the plague. When Susanna reveals that Adam was actually murdered, Isabel is compelled to take up an impossible task: discover the truth about her brother's death, twelve years after it happened. Isabel's investigation leads her through the gamut of London society, from bear-baiting matches and brothels to the realm of wealthy bankers. But as she uncovers her brother's dark secrets, Isabel begins to wonder whether the past is better left buried—especially when uncovering the truth could lead to her own funeral.