Five years after a series of Dante-inspired killings stunned Boston, a politician is found in a London park with his neck crushed by an enormous stone device etched with a verse from the "Divine Comedy." When other shocking deaths erupt across the city, all in the style of the penances Dante memorialized in "Purgatory," poet Christina Rossetti fears that her missing brother, the artist and writer Dante Gabriel Rossetti, will be the next victim. The unwavering Christina enlists poets Robert Browning, Alfred Tennyson and Dr. Oliver Wendell Holmes to decipher the literary clues, and together these unlikely investigators unravel the secrets of Dante’s verses to find Gabriel and stop the killings.