The book is set in Medieval England sometime near the end of the 14th century and the events described in the book take place in an unnamed village in Northern England (north of the Humber).
A priest fleeing from his diocese joins up with a group of travelling players. The players are travelling toward their liege lord's castle where they are expected to play at Christmas but, short of money, they decide to stage their plays at a village en route.
When a morality play from their usual repertoire fails to earn them enough money, Martin, the leader of the group convinces them to stage 'the play of Thomas Wells', a play based on the story of the murder of a young boy from the village.
The murderer has already been found, a young woman from the village, and the play seems simple enough, however they soon find that the facts don't fit. The line between the play and reality blurs and, line-by-line, they arrive at the truth about the murder.