Victorian England. In Yorkshire, several men and horses working on a railway line have been killed. The police suspect some kind of wild beast. The government calls on controversial naturalist Charles Darwin to help with the investigation. A reasonable move, but one that is dicatated rather by the least known part of his work: research on what other people would qualify as legendary creatures. It won't be long before the scientist discovers that he may be right about them after all...

The beast was believed to be dead, but now the body has been stolen and its escort massacred. A woman has been killed inside the town. And the neo-Druids have been slaughtered by what they believed to be their god. Even more disturbing, Charles Darwin is revealed to be one of the creatures! The naturalist can no longer deny his dual nature as he struggles with the terrifying question: could he be the murderous beast that committed the latest murders?