Following the death of her long-time companion, Harriet, Miss Julia Garnet , a retired British schoolteacher, decides to take an appartment in Venice for six months. Venice has a magical effect on reserved Julia: a dyed-in-the-wool Communist, she relaxes in her antipathy toward religion, and even begins to visit the local church. There, she becomes enamored of a series of paintings that tell the story of the Apocryphal book of Tobit, and his journey with the Archangel Raphael. Julia falls in love with an art dealer, Carlo, and befriends Sarah and Toby, twins working on the restoration of a Venetian chapel. When Toby disappears suddenly, after discovering a priceless Renaissance painting, Julia finds out that neither Carlo nor the twins are exactly what they seem--but that the Angel Raphael's watchful spirit will help good prevail.