The story is set in England in the early summer of 1261. The background to the story is the conflict between Henry III and the barons, led by the Duke of Leicester, Simon de Montfort. The main character is Stephen de Grenested who is a stone mason working on the new Westminster Abbey. Stephen, though a talented stone mason is lazy and drinks heavily, thus curtailing a promising career. On Ascension Day, while on holiday, Stephen witnesses the murder of a nun, Sister Scholastica who is the unpopular prioress of a nearby convent. A statue is pushed from the roof of the convent, killing Sister Scholastica. Stephen's brother, Andrew is accused of the murder and eventually locked up by the sheriff. Stephen seeks to clear Andrew's name.