Chaucer's pilgrims, quarreling among themselves, are in the open countryside enjoying the fresh spring weather as they progress slowly toward Canterbury. A motley collection of travelers, they each have their own dark secrets, hidden passions, and complex lives. As they seek shelter in a tavern from an April shower, they choose the Man of Law to follow the Knight and narrate the evening tale.

His story begins in August 1358, with the death of Dowager Queen Isabella, mother of King Edward III, the "She Wolf of France," who betrayed and destroyed her husband because of her adulterous infatuation with Roger Mortimer. According to the Man of Law, Isabella's body is taken along the Mile End Road and laid to rest in Greyfriars next to the mangled remains of her lover, who has paid dearly for his presumption in loving a queen. Nevertheless, as in life so in death Isabella causes intrigue, violence, and murder.

On the day of her burial, her trusted squire attempts to flee to France, possibly carrying a document discrediting the English king. But, captured and grievously wounded, he dies before revealing his secrets. A young lawyer, Nicholas Chirke, is hired to investigate, but soon finds himself pursued by assassins and French agents, and the terrible secrets Isabella carried to her death.