The last novel by Nathaniel Hawthorne paints a surreal picture of guilt, love and responsibility when describing the adventures of three Americans and one Italian in the eternal city of Rome. The book starts by introducing the characters. The first is Kenyon, an American sculptor who comes to Rome to study the Ancients. In his footsteps are Hilda and Miriam, two art students with different backgrounds. Finally, the Italian count Donatello, a friend of the group is introduced. The Italian is compared to the statue of a Faun by Praxiteles, alluding to his lack of conscience and general ease of mind.
Hawthorne's story takes many detours, describing in detail Ancient Art and the beauty of the city. Miriam, the passionate and exotic woman from New England has a chance encounter with a stranger in the catacombs. From this point onward, the stranger stalks her through the city, never far behind.
During a nighttime excursion to the Capitoline Hill, the stranger approaches her. Donatello, madly obsessed with Miriam by this point cannot take this and murders the man in cold blood. This act takes changes Donatello, transforming him into a man riddled with guilt and remorse. The innocent Hilda, originally from a Puritan background, has witnessed the act and is crushed by the secret. In her desperation, she decides to confess to the Catholic Church.
The book ends when Donatello can finally no longer take his guilt and gives himself up to justice. Hilda, deeply affected by what she has seen, agrees to marry Kenyon. Miriam, the one truly affected, becomes deeply depressed and disappears.