In 11th-century England, Abbess Cecily hosts a dinner at Shaftesbury Abbey. Among the guests are Cecily's half brother, Tirel, a knight and world-weary veteran of the Crusades, Sir Baudri de Beaumont and his lovely wife, Beatrice, and Beatrice's look-alike sister Sophina. As minstrels, jugglers, and acrobats amuse the diners, Beatrice suddenly collapses in agony and breathes her last. It now falls to Dame Averilla, a headstrong young nun, Sir Tirel, and Bailiff Robert Bradshaw to investigate. The three must determine whether a crime has indeed been committed, or whether the death, which appears to have been caused by poisoned food, was a dreadful accident. In the process, they discover that the woman who actually succumbed to the poison might not have been Beatrice, and that the murder may have arisen either from jealousy and avarice among the nobility, or was a politically driven outrage ordered by King Henry himself.