An art history graduate student stumbles upon the love of her life and a long-lost manuscript at a medieval monastery outside Orvieto in Umbria. The manuscript records the memories of a monk, Brother Matteo, who in 1263--as a thirteen-year-old foundling, with his Master, his Lady, and his "brother," the gentle giant Giorgio--became part of an unofficial investigation into the newly reported miracle in the ancient town of Bolsena. According to the report, when Father Peter of Bohemia said the words of consecration ("This is My Body") at a pilgrims' mass, the communion host bled Christ's blood onto the altar cloth. In the course of their investigation, Matteo and his family are drawn into the political turmoil of the times, and Matteo learns that this world is, after all, a vale of tears--but also a place of miracles.