It is 15th century Germany. Leon Frey and his cousin, Viktor, are young scholars of the supernatural, keeping their studies away from the watchful gaze of their predominately religious townfolk. When their gypsy mentor, Miri, returns to their hometown of Schattenholz, she brings with her a gift for the two men. It is a book of demons, listing and explaining numerous demonic creatures seen on the Earth. Leon is smitten with the book, and finds that a demon was sighted in the forest outside of his town. Throwing caution to the wind, Leon sets off to find the demon in hopes of learning more about it. What he finds is nothing he could have expected. Leon's life--and the lives of his friends and family--is about to be sent spiraling.