Twenty-year-old Madeleine Karno, daughter of French pathologist Dr. Albert Karno (also known as Dr. Death), takes a keen interest in science and assists her father with his cases. This is unusal, because the year is 1894 and such pursuits are considered inappropriate for women.
When seventeen-year-old Cecile Montaine - a student at the school run by St. Bernardine Convent in Varbourg - is found dead in the snow Madeleine and her father cannot find a cause of death. They do, however, discover odd mites exiting Cecile's nostrils. Soon afterwards the priest who prayed over Cecile's corpse is murdered and his body stolen. Moreover, a teenage boy who worked at St. Bernardine's is missing. Clearly something odd is going on.
Madeleine consults Dr. August Dreyfuss, a leading Heidelberg parasitologist, about the mites and learns they're usually found in dogs. Turns out St. Bernardine Convent is home to a pack of wolves (for superstitious reasons) and Mother Filippa, the abbess, keeps an elderly male wolf as a pet. So dog mites...wolves...things start to gel a little bit.
As the story goes on more deaths occur, dead bodies are found to have bite marks from human teeth, the mites are associated with a bacterial disease, a young lady seems to be hypersexual, a young novice nun is at odds with her father, Dr. Dreyfuss takes a shine to Madeleine, and so on. There's a lot going on and the story gets confusing. There are also a great many characters, some better developed than others.
The book's finale, though thoroughly explained, is complex, hard to believe, and not totally satisfying. All in all, I thought the book was okay. It does address some interesting concepts and I like Madeleine, a spirited young woman determined to follow her dream against all odds.