The year is 1870. Five years after a series of Dante-inspired killings disrupted Boston, a man is found murdered in the public gardens of London with an enormous stone around his neck etched with a verse from the Divine Comedy. When more mysterious murders erupt across the city, all in the style of the punishments Dante memorialized in Purgatory, poet Christina Rossetti fears her brother, the Dante-obsessed artist and writer Gabriel Rossetti, will be the next victim. Christina enlists poets Robert Browning and Alfred Tennyson, and famous scholar Dr. Oliver Wendell Holmes, to assist in deciphering the literary clues. Together these unlikely investigators rush to unravel the secrets of Dante's verses in order to find Gabriel and stop the killings. Racing between the shimmering mansions of the elite and the dark corners of London's underworld, they descend further and further into the mystery. But when the true inspiration behind the gruesome murders is finally revealed, Christina realizes that the perpetrator has even bigger and more horrific plans than she had initially thought.