Plot Summary:Nancy Dewar's hooded corpse is found in a river, having left her alcoholic husband Michael to live with art historian Philip Hamilton. Her death resembles that of a woman in a fresco Hamilton is restoring at a local church. Michael names shopkeeper Ewan Evans as his alibi and whilst Ewan is perturbed that his art student son Noah has a book depicting medieval tortures, the reverend Martha Hillcott hopes to sell a cottage on church land belonging to previous vicar, the ailing Arthur Gould and his daughter Ava, to raise money to save the frescoes from rising river water. On the night she died, Nancy, as one of the church council, was about to sell her vote to Martha to support the sale of the cottage. But then two more murders occur, both styled after pictures in the frescoes. As the river bursts its banks and villagers take refuge in the church, Barnaby works out that the killings were not based in religion but perpetrated to keep hidden a shameful secret, a case less of Let Us Pray than Let Us Prey.