It is December 1888. Jack the Ripper has not killed for over a month and London is beginning to relax as Christmas approaches. When Katherine Kramer cuts herself on a strange book at a dinner party, she quickly falls ill. Her husband Richard is a professor of medicine, but even his efforts are futile as the mysterious illness blazes through her. As Katherine dies, she gives birth to something nightmarish. Something which should not exist. Something which spurs Richard to embark on a terrifying journey of discovery as he chases the answer to one question: who or what killed his wife?