Long after the event, Mary Shelley would recall the crucible out of which her most famous fictional progeny was fused. "In the summer of 1816, we visited Switzerland, and became the neighbors of Lord Byron.... But it proved a wet, ungenial summer, and incessant rain often confined us for days to the house. Some volumes of ghost stories, translated from the German and French, fell into our hands...." After reading several of these tales of dead lovers and inconsolable ghosts, a better idea was struck upon by the gathered company. "'We will each write a ghost story,' said Lord Byron, and his proposition was acceded to."

As Mary Shelley wrote in her 1831 introduction to the revised edition of Frankenstein; or, The New Prometheus, the company--including herself, her soon-to-be husband, the poet Percy Bysshe Shelley, Byron, and his doctor, John William Polidori--all set to work coming up with fabulous...