Madeleine Karno is eager to shatter the constraints of her provincial French upbringing. She wants to become a pathologist like her father, but this is 1894, and autopsies are considered unseemly and ungodly, even when performed by a man. When Cecile Montaine is found dead in the snowy streets of Varbourg, her family will not permit an autopsy, and Madeleine and her father are left with a single mysterious clue: in the dead girl's nostrils they find a type of parasite normally seen only in dogs. Then the priest who held vigil by the corpse is brutally murdered. The thread that connects these two events is a tangled one.