Sister Frevisse has made an unusual journey to London to meet the new prioress of St. Frideswide's. At the urging of her abbot, she stays with her wealthy cousin Alice, lady wife of the earl of Suffolk.
But Frevisse suspects more is involved than a friendly visit - for this London home houses a secret that has turned Alice is involved in the dangerous political machinations of the Duke of Orleans and King Henry VI. Their private correspondence is being routed through the Suffolk's home. But when one of the messengers dies under mysterious circumstances and Frevisse is asked to carry letters in his place, she finds herself faced with a deadly Can she find the traitor before the murderer strikes again when she herself has become the target?